ios 带有块的 Objective-C 延迟动作
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Objective-C delay action with blocks
提问by Sergey Grischyov
I know that there are several ways of delaying an action in Objective-C like:
我知道在 Objective-C 中有几种延迟操作的方法，例如：
performSelector:withObject:afterDelay:
or using NSTimer.
或使用NSTimer.
But there is such a fancy thing called blocks where you can do something like this:
但是有一种叫做块的奇特东西，您可以在其中执行以下操作：
[UIView animateWithDuration:1.50 delay:0 options:(UIViewAnimationOptionCurveEaseOut|UIViewAnimationOptionBeginFromCurrentState) animations:^{
}completion:^(BOOL finished){
}];
Unfortunately, this method applies only to animating things.
不幸的是，这种方法仅适用于动画事物。
How can I create a delay with a block in one methodso I don't have to use all those @selectorsand without the need to create a new separate method? Thanks!
如何在一种方法中使用块创建延迟，以便我不必使用所有这些@selectors并且无需创建新的单独方法？谢谢！
回答by Martin Ullrich
use dispatch_after:
使用 dispatch_after：
double delayInSeconds = 2.0;
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PER_SEC);
dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
//code to be executed on the main queue after delay
[self doSometingWithObject:obj1 andAnotherObject:obj2];
});
回答by rckehoe
Expanding on the accepted answer, I created a Helper function for anyone who doesn't care to memorize the syntax each time they want to do this :) I simply have a Utils class with this:
扩展已接受的答案，我为任何不想记住语法的人创建了一个 Helper 函数，他们每次想要这样做:) 我只是有一个 Utils 类：
Usage:
用法：
[Utils delayCallback:^{
//--- code here
} forTotalSeconds:0.3];
Helper method:
辅助方法：
+ (void) delayCallback: (void(^)(void))callback forTotalSeconds: (double)delayInSeconds{
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PER_SEC);
dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
if(callback){
callback();
}
});
}
回答by Esqarrouth
Here is how you can trigger a block after a delay in Swift:
以下是在 Swift 中延迟后触发块的方法：
runThisAfterDelay(seconds: 4) { () -> () in
print("Prints this 4 seconds later in main queue")
// Or just call animatedMyObject() right here
}
/// EZSwiftExtensions
func runThisAfterDelay(seconds seconds: Double, after: () -> ()) {
let time = dispatch_time(DISPATCH_TIME_NOW, Int64(seconds * Double(NSEC_PER_SEC)))
dispatch_after(time, dispatch_get_main_queue(), after)
}
Its included as a standard function in my repo: https://github.com/goktugyil/EZSwiftExtensions
它作为标准函数包含在我的 repo 中：https: //github.com/goktugyil/EZSwiftExtensions
