Objective-C时间延迟 [英] Objective-C Time Delay

问题描述

每当一个函数循环一个循环时，我希望能够执行一个延迟。我已经有一个循环设置，如下所示：

  for（float batteryPercentage = 1; batteryPercentage <= 0; batteryPercentage  - = 0.01）
 {
 double timeUntilNextDegreeDrop = 9.0; 
 dispatch_time_t time = dispatch_time（DISPATCH_TIME_NOW，（int64_t）（timeUntilNextDegreeDrop * NSEC_PER_SEC））; 
 dispatch_after（time，dispatch_get_main_queue（），^（void）
 {
 [batteryLevel setProgress：batteryPercentage animated：YES]; 
 
 float batteryLevelPercentage = batteryPercentage * 100; 
 batteryLevelLabel.text = [NSString stringWithFormat：@Battery Level：％f %%，batteryLevelPercentage]; 
}）; 
 
  

batteryPercentage 是变量，我试图从1到0每9秒递减0.01，直到值达到0.程序的总长度应该是900秒（15分钟）。每9秒钟，我希望此代码每9秒执行一次，并更改名为 batteryLevel 的 UIProgressView 的值。然后，我想将 batteryPercentage 乘以100，得到一个整数百分数，例如乘以0.67得到67，然后替换 batteryLevelLabel 文本与新值。当我尝试执行此操作时， batteryLevel Progress View不会填充，文本也不会更改。我假设定时器有什么问题，那么输入一个9秒延迟的更有效的方法是什么？解决方案

>按照建议尝试使用nstimer



  [NSTimer scheduledTimerWithTimeInterval：9.0 
 target：self 
 selector：@selector （targetMethod :) 
 userInfo：nil 
 repeats：YES]; 
  





// targetMethod每9秒调用
//调用
[myTimer invalidate]; myTimer = nil; 任务完成时

I want to be able to execute a delay every time that a function loops through a loop. I already have a loop setup, as shown below:

for (float batteryPercentage = 1; batteryPercentage <= 0; batteryPercentage -= 0.01)
    {
        double timeUntilNextDegreeDrop = 9.0;
        dispatch_time_t time = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(timeUntilNextDegreeDrop * NSEC_PER_SEC));
        dispatch_after (time, dispatch_get_main_queue(), ^(void)
        {
            [batteryLevel setProgress:batteryPercentage animated:YES];

            float batteryLevelPercentage = batteryPercentage * 100;
            batteryLevelLabel.text = [NSString stringWithFormat:@"Battery Level: %f%%", batteryLevelPercentage];
        });
    }

batteryPercentage is the variable that I am trying to decrement from 1 to 0 by 0.01 every 9 seconds until the value reaches 0. The total length of the program should be 900 seconds (15 minutes). Every 9 seconds, I want this code to execute every nine seconds and to change the value of the UIProgressView called batteryLevel. Then, I want to multiply batteryPercentage by 100, to get a whole percentage number, such as multiplying 0.67 to get 67, then replace the batteryLevelLabel text with the new value. When I try and execute this, the batteryLevel Progress View simply doesn't fill and the text doesn't change. I'm assuming there's something wrong with the timer, so what would be a more effective way of inputing a 9 second delay?

解决方案

try with nstimer as suggested

[NSTimer scheduledTimerWithTimeInterval:9.0
target:self
selector:@selector(targetMethod:)
userInfo:nil
repeats:YES];

//targetMethod will be called every 9 second //call [myTimer invalidate]; myTimer = nil; when your task is done

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