Question

我这里有问题......

按下按钮后，我想要一个循环运行，直到达到条件：

- (IBAction)buttonclick1 ...

if ((value2ForIf - valueForIf) >= 3) { ...

我希望循环运行直到

((value2ForIf - valueForIf) >= 3)

然后执行与IF语句关联的代码。

我想要实现的是在继续代码之前继续检查上述陈述是否为真的程序。除此之外，IF下面还有一个else语句，但我不知道这是否会影响循环。

我不确定此处所需的循环格式以及我尝试的所有内容都会导致错误。任何帮助将不胜感激。

斯图

Answer 1

除非运行紧密循环，否则会阻止您的应用执行，除非在另一个线程上运行，您可以使用NSTimer以您选择的时间间隔调用方法并检查该方法中的条件。如果满足条件，则可以使计时器无效并继续。

Answer 2

- (IBAction)buttonclick1 ...
{
  //You may also want to consider adding a visual cue that work is being done if it might
  //take a while until the condition that you're testing becomes valid.
  //If so, uncomment and implement the following:

  /*
   //Adds a progress view, note that it must be declared outside this method, to be able to
   //access it later, in order for it to be removed
   progView = [[MyProgressView alloc] initWithFrame: CGRectMake(...)];
   [self.view addSubview: progView];
   [progView release];

   //Disables the button to prevent further touches until the condition is met,
   //and makes it a bit transparent, to visually indicate its disabled state
   thisButton.enabled = NO;
   thisButton.alpha = 0.5;
  */

  //Starts a timer to perform the verification
  NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval: 0.2
                            target: self
                            selector: @selector(buttonAction:)
                            userInfo: nil
                            repeats: YES];
}


- (void)buttonAction: (NSTimer *) timer
{
  if ((value2ForIf - valueForIf) >= 3)
  {
    //If the condition is met, the timer is invalidated, in order not to fire again
    [timer invalidate];

    //If you considered adding a visual cue, now it's time to remove it
    /*
      //Remove the progress view
      [progView removeFromSuperview];

      //Enable the button and make it opaque, to signal that
      //it's again ready to be touched
      thisButton.enabled = YES;
      thisButton.alpha = 1.0;
    */

    //The rest of your code here:
  }
}

Answer 3

根据你的说法，你想要的是一个while循环

while( (value2ForIf - valueForIf) < 3 ) { ...Code Here... }

只要值的差值小于3，这将在大括号中运行代码，这意味着它将运行直到它们的差值为3或更大。但正如亚萨里恩所说。这是一个坏主意，因为你将阻止你的程序。如果代码本身正在更新值，那很好。但是，如果用户正在通过某些UI更新它们，则while循环将阻止UI并且不允许用户输入任何内容。

循环直到达到状态，iPhone

3 个答案: