NSTimer具有匿名功能/块？

Question

我希望能够在将来安排三个小事件,而不必为每个事件编写一个函数.我怎么能用这个NSTimer呢？我理解块有助于匿名功能,但它们可以在内部使用NSTimer,如果是,如何使用？

[NSTimer scheduledTimerWithTimeInterval:gameInterval  
         target:self selector:@selector(/* I simply want to update a label here */) 
         userInfo:nil repeats:NO];

Answer 1

如果要实现类似于NSTimer和块执行的操作,可以使用dispatch_after.

以下是相同的示例代码:

    int64_t delayInSeconds = gameInterval; // Your Game Interval as mentioned above by you

    dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PER_SEC);

    dispatch_after(popTime, dispatch_get_main_queue(), ^(void){

        // Update your label here. 

    });

希望这可以帮助.

Answer 2

你实际上可以打电话:

NSTimer.scheduledTimerWithTimeInterval(ti: NSTimeInterval,
                    target: AnyObject, 
                    selector: #Selector, 
                    userInfo: AnyObject?, 
                    repeats: Bool)

像这样使用它:

NSTimer.scheduledTimerWithTimeInterval(1, 
                    target: NSBlockOperation(block: {...}), 
                    selector: #selector(NSOperation.main), 
                    userInfo: nil, 
                    repeats: true)

Answer 3

Cocoa中存在基于块的计时器API(从iOS 10+/macOS 10.12+开始) - 以下是如何在Swift 3中使用它:

Timer(timeInterval: gameInterval, repeats: false) { _ in
    print("herp derp")
}

......或在Objective-C中:

[NSTimer scheduledTimerWithTimeInterval:gameInterval repeats:NO block:^(NSTimer *timer) {
    NSLog(@"herp derp");
}];

如果您需要定位早于iOS10,macOS 12,tvOS 10,watchOS 3的操作系统版本,则应使用其他解决方案之一.

Answer 4

Objective-C版@Peter Peng的答案:

_actionDelayTimer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:[NSBlockOperation blockOperationWithBlock:^{
    NSLog(@"Well this is useless.");
}] selector:@selector(main) userInfo:nil repeats:YES];

Answer 5

这很简单,但它不包含在Apple框架中,至少还没有.

您可以为NSTimer自己编写基于块的包装器,例如使用GCD,或者您可以使用现有的第三方库,如下所示:https://github.com/jivadevoe/NSTimer-Blocks.