XWCountDownButton_OC
应用场景：可以应用于短信验证码倒计时；
To run the example project, clone the repo, and run pod install from the Example directory first.
XWCountDownButton_OC is available through CocoaPods. To install it, simply add the following line to your Podfile:
pod 'XWCountDownButton_OC'XWCountDownButton_OC is available under the MIT license. See the LICENSE file for more info.