在objective-c中使用基于Time的ProgressBar

Question

嗨，我想在我的iPhone应用程序中根据时间使用进度条，如果一个人开始旅程从上午10:00开始并在11:00结束然后每5分钟我将更新进度与当前时间相比，它是怎么回事可能

Answer 1

You could use a simple NSTimer to achieve this:

In viewDidLoad of course, these variables will need to be declared in your header file.

UIProgressView *myProgressView = [[UIProgressView alloc] initWithProgressViewStyle:UIProgressViewStyleDefault];
float someFloat = 0;

NSTimer *myTimer = [NSTimer scheduledTimerWithTimeInterval:300 target:self selector:@selector(methodToUpdateProgress) userInfo:nil repeats:YES];

Then this will update the progress view (assuming min/max value is 0-100)

- (void)methodToUpdateProgress
{
    if(someFloat == 100){
         [myTimer invalidate];
    }else{
         someFloat = someFloat + 12;
         [myProgressView setProgress:someFloat animated:YES];
    }
}

Additionally, if the time at which this is called is actually a concern this example should help you a lot. Quoted From: How do I use NSTimer?

NSDate *d = [NSDate dateWithTimeIntervalSinceNow: 60.0];
NSTimer *t = [[NSTimer alloc] initWithFireDate: d
                              interval: 1
                              target: self
                              selector:@selector(onTick:)
                              userInfo:nil repeats:YES];

NSRunLoop *runner = [NSRunLoop currentRunLoop];
[runner addTimer:t forMode: NSDefaultRunLoopMode];
[t release];

NOTE: This is a pretty rough example, but it should get the point across. Hope this helps!

Answer 2

iVars:

NSDate *_startDate = ....
NSDate *_finishDate = ....
UIProgressBarView *_progressBar = ....

triggerMethod:

- (void)start
{
   [self updateProgressBar];
   NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:updateInterval 
                                                     target:self 
                                                     selector:@selector(updateProgressBar) 
                                                     userInfo:nil 
                                                     repeats:YES];
}

update progressbarview

- (void)updateProgressBar
{
     NSTimeInterval diff = [_finishDate timeintervalSince:_startDate];
     NSTimeInterval pastTime = [_finishDate timeIntervallSinceNow];
     [_progressBar setProgress:pastTime/diff animated:YES];

}

Do not forget to invalidate timer when it is finished and in dealloc method.

If you save your finish and start date somewhere else in your code. Then you can recreate the view with same state even it is deallocated. It means the user do not need have open that view 1 hour. eg. he/she close and open after 30 min.