我使用动画来指定提示，以帮助延迟交互:
let delay = 1.8 * Double(NSEC_PER_SEC)
let time = dispatch_time(DISPATCH_TIME_NOW, Int64(delay))
dispatch_after(time, dispatch_get_main_queue()) {
//call the method which have the steps after delay.
self.rain.alpha = 0
UIView.animateWithDuration(5, animations: {
self.rain.alpha = 1
})
self.tip.startAnimating()
}
但是，如果在动画开始之前，用户触摸了屏幕，我需要停止这个延迟过程。
最佳答案
iOS 8 和 OS X Yosemite 引入了 dispatch_block_cancel 允许您在它们开始执行之前取消它们
你在类中声明一个变量如下:
var block: dispatch_block_t?
初始化block变量并在dispatch_after中提供:
block = dispatch_block_create(DISPATCH_BLOCK_INHERIT_QOS_CLASS) {
print("I executed")
}
let time: dispatch_time_t = dispatch_time(DISPATCH_TIME_NOW, Int64(5 * NSEC_PER_SEC))
dispatch_after(time, dispatch_get_main_queue(), block!)
之后您可以按如下方式取消它:
dispatch_block_cancel(block!)
关于swift - 停止 dispatch_after，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/28356263/