在早期版本的Swift中，可以使用以下代码创建延迟:
let time = dispatch_time(dispatch_time_t(DISPATCH_TIME_NOW), 4 * Int64(NSEC_PER_SEC))
dispatch_after(time, dispatch_get_main_queue()) {
//put your code which should be executed with a delay here
}
但是现在，在Swift 3中，Xcode自动更改了6个不同的东西，但随后出现了以下错误:“不能转换DispatchTime。现在转换为期望值dispatch_time_t aka UInt64。”
在Swift 3中，如何在运行一段代码序列之前创建一个延迟?
当前回答
// x秒后运行函数
public static func runThisAfterDelay(seconds: Double, after: @escaping () -> Void) {
runThisAfterDelay(seconds: seconds, queue: DispatchQueue.main, after: after)
}
public static func runThisAfterDelay(seconds: Double, queue: DispatchQueue, after: @escaping () -> Void) {
let time = DispatchTime.now() + Double(Int64(seconds * Double(NSEC_PER_SEC))) / Double(NSEC_PER_SEC)
queue.asyncAfter(deadline: time, execute: after)
}
/ /使用:-
runThisAfterDelay(seconds: x){
//write your code here
}
其他回答
经过大量的研究，我终于明白了这一点。
DispatchQueue.main.asyncAfter(deadline: .now() + 2.0) { // Change `2.0` to the desired number of seconds.
// Code you want to be delayed
}
这在Swift 3和Swift 4中创建了理想的“等待”效果。
受到这个答案的启发。
尝试以下在Swift 3.0及以上版本中实现的功能
func delayWithSeconds(_ seconds: Double, completion: @escaping () -> ()) {
DispatchQueue.main.asyncAfter(deadline: .now() + seconds) {
completion()
}
}
使用
delayWithSeconds(1) {
//Do something
}
// x秒后运行函数
public static func runThisAfterDelay(seconds: Double, after: @escaping () -> Void) {
runThisAfterDelay(seconds: seconds, queue: DispatchQueue.main, after: after)
}
public static func runThisAfterDelay(seconds: Double, queue: DispatchQueue, after: @escaping () -> Void) {
let time = DispatchTime.now() + Double(Int64(seconds * Double(NSEC_PER_SEC))) / Double(NSEC_PER_SEC)
queue.asyncAfter(deadline: time, execute: after)
}
/ /使用:-
runThisAfterDelay(seconds: x){
//write your code here
}
一种方法是使用DispatchQueue.main.asyncAfter，正如很多人回答的那样。
另一种方法是使用perform(_:with:afterDelay:)。详情请点击这里
perform(#selector(delayedFunc), with: nil, afterDelay: 3)
@IBAction func delayedFunc() {
// implement code
}
试试下面的延迟代码
//MARK: First Way
func delayForWork() {
delay(3.0) {
print("delay for 3.0 second")
}
}
delayForWork()
// MARK: Second Way
DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) {
// your code here delayed by 0.5 seconds
}
