本文对应github地址Tip001,如果由于github调整导致资源找不到，请访问github

0. 防止暴力点击

防止collection短时间点击多个item

 // �其实并不太友好(慎用)
 [collectionView setUserInteractionEnabled:NO];
 [collectionView performSelector:@selector(setUserInteractionEnabled:) withObject:[NSNumber numberWithBool:YES] afterDelay:0.05f];

防止短时间点击两个按钮

 [view setExclusiveTouch:YES];
 
 // 一个一个设置太麻烦了，可以全局设置
 // [[UIView appearance] setExclusiveTouch:YES];

 // 或者只设置button
 // [[UIButton appearance] setExclusiveTouch:YES];

防止按钮短时间多次点击

 - (void)todoSomething:(id)sender {
     // 在这里做真正的事情
 }
 - (void)handleButtonClick:(UIButton *)sender {
 	// 先将未到时间执行前的任务取消。 
 	[[self class] cancelPreviousPerformRequestsWithTarget:self selector:@selector(todoSomething:) object:sender];
 	// 取消全部可能存在的延迟执行
 	// [[self class] cancelPreviousPerformRequestsWithTarget:self];
   	[self performSelector:@selector(todoSomething:) withObject:sender afterDelay:0.2f];
 }

1. 打印View根视图所有子视图

比如在 -viewDidAppear: 打断点，在控制台输入
```
 po [self.view.superview recursiveDescription]
```

2. layoutSubviews调用时机

当视图第一次显示的时候会被调用
当这个视图显示到屏幕上了,点击按钮
添加子视图也会调用这个方法
当本视图的大小发生改变的时候是会调用的
当子视图的frame发生改变的时候是会调用的
当删除子视图的时候是会调用的
layoutIfNeed

3. NSString去掉首尾某些字符

只针对首/尾

 // 去掉首尾存在的 , 
 NSCharacterSet *set = [NSCharacterSet characterSetWithCharactersInString: @","];
 NSString *newString = [trimString stringByTrimmingCharactersInSet:set];

4. CGAffineTransform属性

平移、旋转、缩放、复原

 // 平移按钮
 CGAffineTransform transForm = self.buttonView.transform;
 self.buttonView.transform = CGAffineTransformTranslate(transForm, 10, 0);
  
 // 旋转按钮
 CGAffineTransform transForm = self.buttonView.transform;
 self.buttonView.transform = CGAffineTransformRotate(transForm, M_PI_4);
  
 // 缩放按钮
 self.buttonView.transform = CGAffineTransformScale(transForm, 1.2, 1.2);
  
 // 初始化复位
 self.buttonView.transform = CGAffineTransformIdentity;

5. 去掉分割线多余15像素(同理设置其他间距)

第一步: viewDidLayoutSubviews 添加

 - (void)viewDidLayoutSubviews {
  if ([self.tableView respondsToSelector:@selector(setSeparatorInset:)]) {
         [self.tableView setSeparatorInset:UIEdgeInsetsZero];    
   }   
  if ([self.tableView respondsToSelector:@selector(setLayoutMargins:)]) {        
         [self.tableView setLayoutMargins:UIEdgeInsetsZero];
   }
 }

第二步: 重写willDisplayCell方法

 - (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell 
 forRowAtIndexPath:(NSIndexPath *)indexPath {   
 	if ([cell respondsToSelector:@selector(setSeparatorInset:)]) {       
     	[cell setSeparatorInset:UIEdgeInsetsZero];    
    	}    
    	if ([cell respondsToSelector:@selector(setLayoutMargins:)]) {        
 		[cell setLayoutMargins:UIEdgeInsetsZero];    
    	}
 }

6. 计算方法耗时时间间隔

两个宏定义

 #define TICK CFAbsoluteTime start = CFAbsoluteTimeGetCurrent();
 #define TOCK NSLog(@"Time: %f", CFAbsoluteTimeGetCurrent() - start)

7. Color颜色宏定义

随机颜色

 #define RANDOM_COLOR [UIColor colorWithRed:arc4random_uniform(256)/255.0 green:arc4random_uniform(256)/255.0 blue:arc4random_uniform(256)/255.0 alpha:1]

颜色(RGBA)

 #define DDYRGBA(r, g, b, a) [UIColor colorWithRed:(r)/255.0f green:(g)/255.0f blue:(b)/255.0f alpha:(a)]

8. UIAlertView

宏定义(不再建议用UIAlertView，推荐UIAlertController)

 #define Alert(_S_, ...) [[[UIAlertView alloc] initWithTitle:@"提示" message:[NSString stringWithFormat:(_S_), ##__VA_ARGS__] delegate:nil cancelButtonTitle:@"确定" otherButtonTitles:nil] show]

9. NSArray 快速求总和最大值最小值和平均值

利用相应keyPath

 NSArray *array = [NSArray arrayWithObjects:@"2.0", @"2.3", @"3.0", @"4.0", @"10", nil];
 CGFloat sum = [[array valueForKeyPath:@"@sum.floatValue"] floatValue];
 CGFloat avg = [[array valueForKeyPath:@"@avg.floatValue"] floatValue];
 CGFloat max =[[array valueForKeyPath:@"@max.floatValue"] floatValue];
 CGFloat min =[[array valueForKeyPath:@"@min.floatValue"] floatValue];
 NSLog(@"%f\n%f\n%f\n%f",sum,avg,max,min);

10. 修改Label中不同文字颜色

转成富文本(attributedText)

 + (__kindof NSMutableAttributedString *_Nonnull)changeTotalString:(NSString *_Nonnull)totalString subStringArray:(NSArray *_Nonnull)subStringArray subStringColor:(UIColor *_Nonnull)color andFont:(UIFont *_Nonnull)font {
     NSMutableAttributedString *attributedStr = [[NSMutableAttributedString alloc] initWithString:totalString];
     for (NSString *rangeStr in subStringArray) {
         NSRange range = [totalString rangeOfString:rangeStr options:NSBackwardsSearch];
         [attributedStr addAttribute:NSForegroundColorAttributeName value:color range:range];
         [attributedStr addAttribute:NSFontAttributeName value:font range:range];
     }
     return attributedStr;
 }

11. 播放声音

需要引入AVFoundation

  // 1.获取音效资源的路径
  NSString *path = [[NSBundle mainBundle]pathForResource:@"sound" ofType:@"wav"];
  // 2.将路径转化为url
  NSURL *tempUrl = [NSURL fileURLWithPath:path];
  // 3.用转化成的url创建一个播放器
  NSError *error = nil;
  AVAudioPlayer *player = [[AVAudioPlayer alloc]initWithContentsOfURL:tempUrl error:&error];
  // 4.播放
  [player play];

12. NSTimer

NSTimer计算的时间并不精确
NSTimer需要添加到runLoop运行才会执行，但是这个runLoop的线程必须是已经开启。
NSTimer会对它的tagert进行retain，我们必须使用intvailte停止。target如果是self甚至weakSelf(控制器自己)，那么VC的retainCount+1，如果你不释放NSTimer，那么你的VC就不会dealloc了，内存泄漏了。
scheduledTimerWithTimeInterval.. 默认已经添加到runloop，timerWithTimeInterval..需要手动添加

可以用NSProxy转发或者block形式避免存在的内存泄漏

 #import "NSTimer+DDYExtension.h"
 #import <objc/runtime.h>
 
 @implementation NSTimer (DDYExtension)
 
 + (NSTimer *)ddy_scheduledTimerWithTimeInterval:(NSTimeInterval)interval repeats:(BOOL)repeats block:(void (^)(NSTimer *timer))block {
     if (@available(iOS 10.0, *)) {
         return [self scheduledTimerWithTimeInterval:interval repeats:repeats block:^(NSTimer * _Nonnull timer) { block(timer); }];
     } else {
         return [self scheduledTimerWithTimeInterval:interval target:self selector:@selector(ddy_timerInvoke:) userInfo:[block copy] repeats:repeats];
     }
 }
 
 + (void)ddy_timerInvoke:(NSTimer *)timer {
     void (^block)(NSTimer *timer) = timer.userInfo;
     if (block) block(timer);
 }
 
 @end

13. 真机调试包[Could not find Developer Disk Image]

下载开发包
强制退出Xcode（必须退出干净）
前往"/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport"粘贴解压缩后的文件(以自己实际路径实际名称)
如果找不到相应真机调试包可以尝试修改文件名(如iOS13.2 -> iOS13.3)

14. UISearchBar 中cancel改成取消

如果层级改变可适当调整

 - (BOOL)searchBarShouldBeginEditing:(UISearchBar *)searchBar {
     searchBar.showsCancelButton = YES;
     for(UIView *view in  [[[searchBar subviews] objectAtIndex:0] subviews]) {
         if([view isKindOfClass:[NSClassFromString(@"UINavigationButton") class]]) {
             UIButton * cancel =(UIButton *)view;
             [cancel setTitle:@" 取消" forState:UIControlStateNormal];
         }
     }
     return YES;
 }

15.截图功能

drawViewHierarchyInRect可截取导航(可以用window截图)

 - (UIImage *)ddy_SnapshotImage {
     UIGraphicsBeginImageContext(self.bounds.size);
     if([self respondsToSelector:@selector(drawViewHierarchyInRect:afterScreenUpdates:)]){
         [self drawViewHierarchyInRect:self.bounds afterScreenUpdates:NO];
     } else{
         [self.layer renderInContext:UIGraphicsGetCurrentContext()];
     }
     UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
     UIGraphicsEndImageContext();
     NSData *imageData = UIImageJPEGRepresentation(image, 0.6);
     image = [UIImage imageWithData:imageData];
     return image;
 }

我只是想要截个屏附 [view snapshotViewAfterScreenUpdates:YES];

16. 获取设备上所有app的bundle id

不知道现在还能不能用

 import <objc/runtime.h>
 
 Class LSApplicationWorkspace_class = objc_getClass("LSApplicationWorkspace");
 NSObject* workspace = [LSApplicationWorkspace_class performSelector:@selector(defaultWorkspace)];NSLog(@"apps: %@", [workspace performSelector:@selector(allApplications)]);

17. iOS 判断图片类型

特征码 JPEG,JPG: 0xFF 0xD8 2字节 JPG是JPEG的缩写
BMP: 0x42 0x4D 2字节
PNG: 0x89 0x50 0x4E 0x47 0x0D 0x0A 0x1A 0x0A 8字节
GIF: 0x47 0x49 0x46 0x38 0x39/ 0x37 0x61 GIF有87a和89a两种格式

 // 通过图片Data数据第一个字节 来获取图片扩展名
 - (NSString *)contentTypeForImageData:(NSData *)data {
     uint8_t c;
     [data getBytes:&c length:1];
     switch (c) {
         case 0xFF:
             return @"jpeg";
         case 0x89:
             return @"png";     
         case 0x47:
         case 0x37:
             return @"gif";        
         case 0x49:   
         case 0x4D:
             return @"tiff";
         case 0x42:
             return @"bmp";        
         case 0x52:  
             if ([data length] < 12) {
                 return nil;
             }
             NSString *testString = [[NSString alloc] initWithData:[data subdataWithRange:NSMakeRange(0, 12)] encoding:NSASCIIStringEncoding];
             if ([testString hasPrefix:@"RIFF"] && [testString hasSuffix:@"WEBP"]) {
                 return @"webp";
             }
             return nil;
     }
     return nil;
 }

其实图片数据的第一个字节是固定的,一种类型的图片第一个字节就是它的标识, 我们来调用一下这个方法:
```
 NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:picPathStr]];
 NSString *string = [self contentTypeForImageData:data]; 
```
参考

18. App迭代开发版本号的规则介绍

1.修复Bug或者优化功能, 我们只修改叠加第三位数字, 其他不变，如1.0.1
2.有了新的需求, 在原基础上增加新功能, 版本号变为1.1.0, 清空第三位为0, 叠加第二位
3.需求功能大改, 更新量非常大, 那我们的版本号变为2.0.0, 需要叠加第一位, 清空其他为0
参考

19. iOS 系统权限介绍

权限管理总结库(参考可按需修改或CV)DDYAuthManager
参考的文章系统权限介绍

20. 私有API实现进入后台(相当于按home键)

谨慎使用

 [[UIApplication sharedApplication] performSelector:@selector(suspend)];  // suspend：暂停;

21. 带有中文的URL处理

URL编码

 // 编码分为不同标准
 NSString *URLStr = @"http://static.tripbe.com/videofiles/视频/我的自拍视频.mp4";
 // NSString *path  = (__bridge_transfer NSString *)CFURLCreateStringByReplacingPercentEscapesUsingEncoding(NULL, (__bridge CFStringRef)URLStr, CFSTR(""), CFStringConvertNSStringEncodingToEncoding(NSUTF8StringEncoding));
 NSString* encodedURLString = [URLStr stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

如果某些特殊符号

 // 我们一般用这个方法处理stringByAddingPercentEscapesUsingEncoding但是这个方法好想不会处理／和&amp;这种特殊符号，这种情况就需要用下边这个方法处理
 @implementation NSString (NSString_Extended)
 - (NSString *)urlencode {
     NSMutableString *output = [NSMutableString string];
     const unsigned char *source = (const unsigned char *)[self UTF8String];
     int sourceLen = strlen((const char *)source);
     for (int i = 0; i &lt; sourceLen; ++i) {
         const unsigned char thisChar = source[i];
         if (thisChar == ' '){
             [output appendString:@"+"];
         } else if (thisChar == '.' || thisChar == '-' || thisChar == '_' || thisChar == '~' || 
                    (thisChar &gt;= 'a' &amp;&amp; thisChar &lt;= 'z') ||
                    (thisChar &gt;= 'A' &amp;&amp; thisChar &lt;= 'Z') ||
                    (thisChar &gt;= '0' &amp;&amp; thisChar &lt;= '9')) {
             [output appendFormat:@"%c", thisChar];
         } else {
             [output appendFormat:@"%%%02X", thisChar];
         }
     }
     return output;
 }

22. 给UIView/UILabel设置图片

使用UIImageView
[view setBackGroundColor:[UIColor colorWithPatternImage:img];

CALayer

 view.layer.contents = (__bridge id)image.CGImage;
 // 设置显示的图片范围,四个值在0-1之间,对应的为x, y, w, h
 view.layer.contentsCenter = CGRectMake(0.25,0.25,0.5,0.5);

23. VC设置背景图片

见上 22

 // 没必要添加UIImageView，直接在layer上画
 self.view.layer.contents = (__bridge id _Nullable)([UIImage imageNamed:@"beijing"].CGImage)

24. view的部分圆角问题

也可以自己设定路径

 UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:view2.bounds byRoundingCorners:UIRectCornerBottomLeft | UIRectCornerBottomRight cornerRadii:CGSizeMake(10, 10)];
 CAShapeLayer *maskLayer = [[CAShapeLayer alloc] init];
 maskLayer.frame = view2.bounds;
 maskLayer.path = maskPath.CGPath;
 view2.layer.mask = maskLayer;
 //其中，
 byRoundingCorners:UIRectCornerBottomLeft | UIRectCornerBottomRight
 /* 指定了需要成为圆角的角，用“|”组合。该参数是UIRectCorner类型的，可选的值有：
 * UIRectCornerTopLeft
 * UIRectCornerTopRight
 * UIRectCornerBottomLeft
 * UIRectCornerBottomRight
 * UIRectCornerAllCorners
 */

25.禁止程序运行时自动锁屏

一般用于视频播放

 [[UIApplication sharedApplication] setIdleTimerDisabled:YES];

26. 常用删除命令

删库跑路，谨慎用之

 # 清空废纸篓 
 sudo rm -rf ~/.Trash/
 # 删除Xcode 编译的数据 
 rm -rf ~/Library/Developer/Xcode/DerivedData/
 # 代码不提示删除 
 rm ~/Library/Caches/com.apple.dt.Xcode
 # pod search 搜不出真的存在的库 zsl 用自己的
 rm ~/Library/Caches/CocoaPods/search_index.json

27. 把tableview里cell的小对勾的颜色改成别的颜色

能自定义的最好自定义

 tableView.tintColor = [UIColor redColor];

28. 修改textFieldplaceholder字体颜色(字号)

iOS13前，

[textField setValue:color forKeyPath:@"_placeholderLabel.textColor"];

iOS13后会crash，可用以下姿势。

姿势一：采用富文本形式

_textField.attributedPlaceholder = [[NSMutableAttributedString alloc] initWithString:placeholder attributes:@{NSForegroundColorAttributeName : color}];

姿势二：new方式创建一个新label（太low不建议用）

// 必须new创建，如果alloc-init创建还是crash(两种方式差别自行google，不是BD)
UILabel * placeholderLabel = [UILabel new];
placeholderLabel.text = @"666";
placeholderLabel.textColor = [UIColor blueColor];
[_textField setValue: placeholderLabel forKey:@"_placeholderLabel"];//new创建这里并没有crash

姿势三：Runtime

Ivar ivar = class_getInstanceVariable([UITextField class], "_placeholderLabel");
UILabel *placeholderLabel = object_getIvar(_textField, ivar);
placeholderLabel.textColor = color;

29.主线程操作UI（对UI进行更新只能在主线程进行）

方法一

 // waitUntilDone:是否线程任务完成执行
 [self performSelectorOnMainThread:@selector(updateImage:) withObject:data waitUntilDone:YES];

方法二

 dispatch_async(dispatch_get_main_queue(), ^{
 	//更新UI的代码，不用主线程中调用
 });

方法三

 // 使用NSOperationQueue
 // 第一种：
     [[NSOperationQueuemainQueue]addOperationWithBlock:^{
         // do something
     }];
 // 第二种:将工作内容封装在NSOperation中，然后
 // [[NSOperationQueue mainQueue] addOperation:myOperation];

30. 两种方法删除NSUserDefaults所有记录

方法一

 NSString *appDomain = [[NSBundle mainBundle] bundleIdentifier];
 [[NSUserDefaults standardUserDefaults] removePersistentDomainForName:appDomain];

方法二

 - (void)resetDefaults {
     NSUserDefaults * defs = [NSUserDefaults standardUserDefaults];
     NSDictionary * dict = [defs dictionaryRepresentation];
     for (id key in dict) {
         [defs removeObjectForKey:key];
     }
     [defs synchronize];
 }

31. UITableView设置Section间距

注意有时候0就不生效了

 // 只设一个可能仍出现20的高度,也不可设置0
 // Header底部间距
 - (CGFloat)tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section {  
     return 40;//section头部高度  
 }  
 // footer底部间距  
 - (CGFloat)tableView:(UITableView *)tableView heightForFooterInSection:(NSInteger)section {  
     return 0.001;  
 }

32.常用GCD总结

详见多线程部分

 // 后台执行： 
 dispatch_async(dispatch_get_global_queue(0, 0), ^{ 
 	// something 
 }); 
 // 主线程执行： 
 dispatch_async(dispatch_get_main_queue(), ^{ 
 	// something 
 }); 
 // 一次性执行： 
 static dispatch_once_t onceToken; 
 dispatch_once(&onceToken, ^{ 
 	// code to be executed once 
 }); 
 // 延迟2秒执行： 
 dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2.0 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
 	// code to be executed after a specified delay
 });

33.tabBarController跳转到另一个一级页面

当我们用tabBarController时，若已经到其中一个TabBar的子页，又要跳转到某一个一级的页面时，如果这样写，导致底部出现黑边，引起tabbar消失的bug
```
 [self.navigationController popToRootViewControllerAnimated:YES];
 ((AppDelegate *)AppDelegateInstance).tabBarController.selectedIndex = 2;
```

解决方法一：删除动画

 [self.navigationController popToRootViewControllerAnimated:NO];
 ((AppDelegate *)AppDelegateInstance).tabBarController.selectedIndex = 2;

解决方法二：延迟执行另一个系统操作

 [self.navigationController popToRootViewControllerAnimated:NO];
 dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.5 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
 	((AppDelegate *)AppDelegateInstance).tabBarController.selectedIndex = 2;
 });

34. WebView获取Html的标题title

UIWebView(即将废除)

 titleLabel.text = [webView stringByEvaluatingJavaScriptFromString:@"document.title"];

WKWebView

 - (void)viewDidLoad {
     [super viewDidLoad];
     [self.wkWebview addObserver:self forKeyPath:@"title" options:NSKeyValueObservingOptionNew context:NULL];
 }
 
 - (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
 	if ([keyPath isEqualToString:@"title"]) {
  		if (object == self.wkWebView) {
 	   		self.title = self.wkWebView.title;
  		} else {
    			[super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
    		}
 	} else {
 		[super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
     }
 }
 
 - (void)dealloc{
     [self.wkWebView removeObserver:self forKeyPath:@"title"];
 }

参考WKWebView获取title和加载进度

35. user-Agent问题

UIWebView(即将废除)

AppDelegate 中 - (BOOL)application: didFinishLaunchingWithOptions:

NSDictionary *dict = @{@"UserAgent":@"appwebkit"};
[[NSUserDefaults standardUserDefaults] registerDefaults:dict];

应用

// 获取webView userAgent
NSMutableString *userAgent = [NSMutableString stringWithString:[[UIWebView new] stringByEvaluatingJavaScriptFromString:@"navigator.userAgent"]];

// 更改UserAgent
NSString *newUagent = [NSString stringWithFormat:@"%@ WMall/%@", userAgent, [SystemInfo appShortVersion]];
NSDictionary *dictionnary = [[NSDictionary alloc] initWithObjectsAndKeys:newUagent, @"UserAgent", nil];
[[NSUserDefaults standardUserDefaults] registerDefaults:dictionnary];

考虑到兼容性，只对某些webview实施自定义UA。[这几个方法一定要是静态方法，要不然设置UA不生效]

NSString* defaultUserAgent = nil;
#pragma mark 获取默认的UA，用于恢复UA
+ (void)initialize {
    if (self == [WebViewController class]) {
        defaultUserAgent =  [[UIWebView new] stringByEvaluatingJavaScriptFromString:@"navigator.userAgent"];
    }
}
#pragma mark 在默认UA后追加自定义UA
+ (void)registeCustomizeWebViewUserAgent {
    UIDevice *device = [UIDevice currentDevice];
    NSString *iOSName = [device systemName];
    NSString *iOSVersion = [device systemVersion];
    NSString *customizeUserAgent = [NSString stringWithFormat:@"xxxxxMobile/%@ (Platform/%@; %@/%@)", APP_SHORT_VERSION, @"iPad", iOSName, iOSVersion];
    NSString *webViewUserAgent = [[UIWebView new] stringByEvaluatingJavaScriptFromString:@"navigator.userAgent"];
    customizeUserAgent = [webViewUserAgent stringByAppendingFormat:@" %@", customizeUserAgent];
    if (customizeUserAgent) {
        [[NSUserDefaults standardUserDefaults] registerDefaults:@{ @"UserAgent": customizeUserAgent}];
    }
}
- (void)dealloc {
    /*由于自定义的userAgent无法播放webview的视频，所以。当webview销毁的时候，重置一下userAgent*/
    [[self class] recoverDefaultUserAgent];
}
+ (void) recoverDefaultUserAgent {
    if (defaultUserAgent) {
        [[NSUserDefaults standardUserDefaults] registerDefaults:@{ @"UserAgent": defaultUserAgent}];
    }
}

WKWebView

 if (@available(iOS 12.0, *)) 
 	NSString *baseAgent = [self.myWebView valueForKey: @"applicationNameForUserAgent"];
   	NSString *userAgent = [NSString stringWithFormat:@"%@ DDY", baseAgent];
   	[self.wkWebView setValue:userAgent forKey:@"applicationNameForUserAgent"];
 }
 
 @ddy_weakify(self);
 [self.wkWebView evaluateJavaScript:@"navigator.userAgent" completionHandler:^(NSString *oldAgent, NSError *error) {
     
     if ([oldAgent rangeOfString:@"DDY"].location != NSNotFound) {
         return;
     }
     NSString *newAgent = [NSString stringWithFormat: @"%@ %@", oldAgent, @"DDY"];
     NSDictionary *dictionary = [NSDictionary dictionaryWithObjectsAndKeys:newAgent, @"UserAgent", nil];
     [[NSUserDefaults standardUserDefaults] registerDefaults:dictionary];
     [[NSUserDefaults standardUserDefaults] synchronize];
     if (@available(iOS 9.0, *)) {
         [weakSelf.myWebView setCustomUserAgent:newAgent];
     } else {
         [weakSelf.myWebView setValue:newAgent forKey:@"applicationNameForUserAgent"];
     }
 }];

36. 汉字转为拼音

利用CoreFoundation

 - (NSString *)Charactor:(NSString *)aString getFirstCharactor:(BOOL)isGetFirst {
     // 转成了可变字符串
     NSMutableString *str = [NSMutableString stringWithString:aString];
     // 先转换为带声调的拼音
     CFStringTransform((CFMutableStringRef)str,NULL, kCFStringTransformMandarinLatin,NO);
     // 再转换为不带声调的拼音
     CFStringTransform((CFMutableStringRef)str,NULL, kCFStringTransformMandarinLatin,NO);
     CFStringTransform((CFMutableStringRef)str, NULL, kCFStringTransformStripDiacritics, NO);
     NSString *pinYin = [str capitalizedString];
     //转化为大写拼音
     if(isGetFirst) {
         // 获取并返回首字母
         return [pinYin substringToIndex:1];
     } else {
         return pinYin;
     }
 }

37. 打印宏定义

优化release，防止打印

 // 处于开发阶段
 #ifdef DEBUG
 #define DDYLog(...) NSLog(__VA_ARGS__)
 //#define DDYInfoLog(fmt, ...) fprintf(stderr,"\nfunction:%s line:%d content:%s\n", __FUNCTION__, __LINE__, ［NSString stringWithFormat:fmt, ##__VA_ARGS__] UTF8String]);
 #define DDYInfoLog(fmt, ...) {\
 NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];\
 [dateFormatter setDateStyle:NSDateFormatterMediumStyle];\
 [dateFormatter setTimeStyle:NSDateFormatterShortStyle];\
 [dateFormatter setDateFormat:@"HH:mm:ss:SSS"]; \
 NSString *str = [dateFormatter stringFromDate:[NSDate date]];\
 fprintf(stderr,"[%s %s %d]: %s\n",[str UTF8String], [[[NSString stringWithUTF8String:__FILE__] lastPathComponent] UTF8String], __LINE__, [[NSString stringWithFormat:fmt, ##__VA_ARGS__] UTF8String]);\
 }
 //#define DDYInfoLog(fmt, ...) NSLog((@"\n[fileName:%s]\n[methodName:%s]\n[lineNumber:%d]\n" fmt),__FILE__, __FUNCTION__, __LINE__, ##__VA_ARGS__)
 // 处于发布阶段
 #else
 #define DDYLog(...)
 #define DDYInfoLog(...)
 #endif

用fprintf 可避免NSLog打印不全问题

38. CocoaPods

CocoaPods教程详见github内 CocoaPods

39. Runtime objc_msgSend报错

Too many arguments to function call ,expected 0,have3

 Project --> Build Settings --> 搜索objc --> ENABLE_STRICT_OBJC_MSGSEND --> 设置NO

40. 3DTouch

详见github内 3DTouch

41. 捕获系统外异常

只用基本

 void UncaughtExceptionHandler(NSException *exception) {
     NSArray  *callStackSymbols = [exception callStackSymbols];
     NSString *callStackSymbolStr = [callStackSymbols componentsJoinedByString:@"\n"];
     NSString *reason = [exception reason];
     NSString *name = [exception name];
     DDYInfoLog(@"异常名称：%@\n异常原因：%@\n堆栈标志：%@",name, reason, callStackSymbolStr);
 }
 
 // - application: didFinishLaunchingWithOptions:
 NSSetUncaughtExceptionHandler(&UncaughtExceptionHandler);

深层次(慎用[影响日志上报工具])

 #import "DDYSafeHeader.h"
 #include <libkern/OSAtomic.h>
 #include <execinfo.h>
 
 // !!!: 崩溃预防
 // 崩溃时发送通知
 NSString *const DDYSafeNotification = @"DDYSafeNotification";
 // 返回nil来防止崩溃
 NSString *const DDYSafeReturnNil = @"DDYSafe return nil to avoid crash";
 // 移除nil来防止崩溃
 NSString *const DDYSafeRemoveNil = @"DDYSafe remove nil to avoid crash";
 // 忽略操作来防止崩溃
 NSString *const DDYSafeIgnore = @"DDYSafe ignore the operation to avoid crash";
 // 消息转发来防止崩溃
 NSString *const DDYSafeForward = @"DDYSafe forward invocation to avoid crash";
 // 返回主线程防止崩溃
 NSString *const DDYSafeMainThread = @"DDYSafe return main thread to avoid crash";
 // 崩溃堆栈信息
 NSString *const DDYSafeCrashStack = @"DDYSafeCrashStack";
 // 异常信息
 NSString *const DDYSafeException = @"DDYSafeException";
 // 解决信息
 NSString *const DDYSafeSolution = @"DDYSafeSolution";
 
 
 // !!!: 崩溃发生
 NSString * const DDYExceptionName = @"DDYExceptionName";
 NSString * const DDYSignalKey = @"DDYSignalKey";
 NSString * const DDYAddressesKey = @"DDYAddressesKey";
 
 volatile int32_t UncaughtExceptionCount = 0;
 const int32_t UncaughtExceptionMaximum = 100;
 
 
 @implementation DDYSafeHeader
 
 #pragma mark - 安全守护，旨在预防
 + (void)ddy_SafeEffective {
     // !!!:防止多次调用
     static dispatch_once_t onceToken;
     dispatch_once(&onceToken, ^{
         [NSObject ddy_SafeEffect];
         [NSArray ddy_SafeEffect];
         [NSMutableArray ddy_SafeEffect];
         [NSDictionary ddy_SafeEffect];
         [NSMutableDictionary ddy_SafeEffect];
         [NSString ddy_SafeEffect];
         [NSMutableString ddy_SafeEffect];
         [NSAttributedString ddy_SafeEffect];
         [NSMutableAttributedString ddy_SafeEffect];
         [NSNull ddy_SafeEffect];
         [UIView ddy_SafeEffect];
         [UITableView ddy_SafeEffect];
     });
 }
 
 #pragma mark - 崩溃发生，防止闪退
 + (void)ddy_HandleUncaughtException {
     NSLog(@"请在断开数据线连接(当然也不允许无线调试)状态测试");
     NSSetUncaughtExceptionHandler(&HandleException);
     signal(SIGABRT, SignalHandler);
     signal(SIGILL,  SignalHandler);
     signal(SIGSEGV, SignalHandler);
     signal(SIGFPE,  SignalHandler);
     signal(SIGBUS,  SignalHandler);
     signal(SIGPIPE, SignalHandler);
 }
 
 #pragma mark 处理异常
 void HandleException(NSException *exception) {
     saveOrUploadException(exception);
     
     int32_t exceptionCount = OSAtomicIncrement32(&UncaughtExceptionCount);
     // 如果太多不用处理
     if (exceptionCount > UncaughtExceptionMaximum) {
         return;
     }
     
     CFRunLoopRef runLoop = CFRunLoopGetCurrent();
     CFArrayRef allModes = CFRunLoopCopyAllModes(runLoop);
     NSArray *allModeArray = (__bridge NSArray *)allModes;
     CFRelease(allModes);
     while (1) {
         for (NSString *mode in allModeArray) {
             CFRunLoopRunInMode((CFStringRef)mode, 0.001, false);
         }
     }
 }
 
 #pragma mark 处理signal报错
 void SignalHandler(int signal) {
     int32_t exceptionCount = OSAtomicIncrement32(&UncaughtExceptionCount);
     
     if (exceptionCount > UncaughtExceptionMaximum) {
         return;
     }
     
     NSString* description = nil;
     switch (signal) {
         case SIGABRT:
             description = [NSString stringWithFormat:@"Signal SIGABRT was raised!\n"];
             break;
         case SIGILL:
             description = [NSString stringWithFormat:@"Signal SIGILL was raised!\n"];
             break;
         case SIGSEGV:
             description = [NSString stringWithFormat:@"Signal SIGSEGV was raised!\n"];
             break;
         case SIGFPE:
             description = [NSString stringWithFormat:@"Signal SIGFPE was raised!\n"];
             break;
         case SIGBUS:
             description = [NSString stringWithFormat:@"Signal SIGBUS was raised!\n"];
             break;
         case SIGPIPE:
             description = [NSString stringWithFormat:@"Signal SIGPIPE was raised!\n"];
             break;
         default:
             description = [NSString stringWithFormat:@"Signal %d was raised!",signal];
     }
     
     NSMutableDictionary *userInfo = [NSMutableDictionary dictionary];
     [userInfo setObject:getAddressKey() forKey:DDYAddressesKey];
     [userInfo setObject:[NSNumber numberWithInt:signal] forKey:DDYSignalKey];
     
     HandleException([NSException exceptionWithName:DDYExceptionName reason:description userInfo:userInfo]);
 }
 
 NSArray *getAddressKey() {
     // 指针列表
     void* callstack[128];
     int frames = backtrace(callstack, 128);
     char **strs = backtrace_symbols(callstack, frames);
     NSMutableArray *backtrace = [NSMutableArray arrayWithCapacity:frames];
     for (int i = 0; i < frames; i++) {
         [backtrace addObject:[NSString stringWithUTF8String:strs[i]]];
     }
     free(strs);
     return backtrace;
 }
 
 #pragma mark 保存或者上传日志
 void saveOrUploadException() {
     
 }
 
 @end

42. Xcode Build Configuration

见github BuildConfiguration

详见github

44. OC中语法糖

界限更鲜明

 self.imageView = ({
     UIImageView *imageView = [[UIImageView alloc] init];
     imageView.image = [UIImage imageNamed:@"12345"];
     imageView.frame = CGRectMake(0, 0, 100, 100);
     [self.view addSubview:imageView];
     imageView;
 });

45.获取当前显示的控制器

能不用最好不用，能不在View中跳转最好别在View中跳转

 + (UIViewController *)findCurrentResponderViewController{ 
 	UIViewController *currentVC = nil; 
 	UIWindow *window = [[UIApplication sharedApplication] keyWindow]; 
 	if (window.windowLevel != UIWindowLevelNormal) { 
 		NSArray *windows = [[UIApplication sharedApplication] windows]; 
 		for(UIWindow *tmpWin in windows) { 
 			if (tmpWin.windowLevel == UIWindowLevelNormal) { 
 				window = tmpWin; break; 
      		}
    		}
  	}
  	UIView *frontView = [[window subviews] objectAtIndex:0]; 
 	id nextResponder = [frontView nextResponder]; 
 	if ([nextResponder isKindOfClass:[UIViewController class]]) {
 		currentVC = nextResponder; 
 	} else  { 
 		UIViewController *topVC = window.rootViewController.presentedViewController; 
 		if (topVC) { 
 			currentVC = topVC; 
 		} else { 
 			currentVC = window.rootViewController;
  		} 
 	} 
 	return currentVC;
 }

view中跳转

 NASkillAptitudeVC *vc = [[NASkillAptitudeVC alloc] init];
     [[self currentViewController].navigationController pushViewController:vc animated:YES];
 
 - (UIViewController *)currentViewController {
     UIResponder *next = self.nextResponder;
     do {
         //判断响应者是否为视图控制器
         if ([next isKindOfClass:[UIViewController class]]) {
             return (UIViewController *)next;
         }
         next = next.nextResponder;
     } while (next != nil);
     
     return nil;
 }

46. UIView虚线框

利用layer

 CAShapeLayer *borderLayer = [CAShapeLayer layer];
 borderLayer.bounds = self.picView.frame;
 borderLayer.position = self.picView.center;
 borderLayer.path = [UIBezierPath bezierPathWithRoundedRect:borderLayer.bounds cornerRadius:3].CGPath;
 borderLayer.lineWidth = 1;
 borderLayer.lineDashPattern = @[@4, @2];
 borderLayer.fillColor = [UIColor clearColor].CGColor;
 borderLayer.strokeColor = [UIColor grayColor].CGColor;
 [self.picView.layer addSublayer:borderLayer];

iOS为UIView添加虚线边框

47. iOS打电话

三种方式对比

打电话的三种方式对比

48. TableViewCell间距

姿势一

 - (void)setFrame:(CGRect)frame {
     // 整体向下 移动10 
     frame.origin.y += 10;
     // 间隔10 
     frame.size.height -= 10;
     [super setFrame:frame];
 }

姿势二

设置背景视图，约束距离

49. 带UITableView的界面出现空白解决

酌情选择里面代码

 - (void)deleteTopBlank { 
 		self.edgesForExtendedLayout = UIRectEdgeNone;
 	   	self.navigationController.navigationBar.translucent = NO;
       	self.automaticallyAdjustsScrollViewInsets = NO;
      	self.extendedLayoutIncludesOpaqueBars = YES
 }

参考美团技术博客

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