更新标题时如何防止UIButton闪烁

问题描述

当我在UIButton上调用setTitle时，该按钮在iOS 7中闪烁。我尝试设置myButton.highlighted = NO，但这并没有阻止按钮闪烁。

When I call setTitle on a UIButton, the button flashes in iOS 7. I tried setting myButton.highlighted = NO, but that didn't stop the button from flashing.

[myButton setTitle:[[NSUserDefaults standardUserDefaults] stringForKey:@"elapsedLabelKey"] forState:UIControlStateNormal];

myButton.highlighted = NO;

以下是我如何设置更新标题的计时器：

Here is how I set up the timer that updated the titles:

- (void)actionTimer {
    if (myTimer == nil) {

        myTimer = [NSTimer scheduledTimerWithTimeInterval: 1.0
                        target: self
                        selector: @selector(showActivity)
                        userInfo: nil
                        repeats: YES];
    }
}

以下是实际更新标题的方法：

Here is the method that actually updates the titles:

- (void)showActivity {

    NSString *sym = [[NSLocale currentLocale] objectForKey:NSLocaleCurrencySymbol];

    if (pauseInterval == nil) {

        // Update clock
        seconds = [[NSDate date] timeIntervalSinceDate:startInterval] - breakTime;

        // Update total earned
        secRate = rate.value / 60 / 60;
        total = secRate * seconds;
        [totalLabel setTitle:[NSString stringWithFormat:@"%@%.4f",sym,total] forState:UIControlStateNormal];

        days = seconds / (60 * 60 * 24);
        seconds -= days * (60 * 60 * 24);
        int hours = seconds / (60 * 60);
        fhours = (float)seconds / (60.0 * 60.0);
        seconds -= hours * (60 * 60);
        int minutes = seconds / 60;
        seconds -= minutes * 60;

        // Update the timer clock
        [elapsed setTitle:[NSString stringWithFormat:@"%.2i:%.2i:%.2i:%.2i",days,hours,minutes,seconds] forState:UIControlStateNormal];
    }
}

推荐答案

闪烁不是由计时器本身引起的。 UIButton方法setTitle：forState导致闪烁。一个简单的解决方法是使用没有标题的UIButton并叠加UILabel。更改UILabel文本时，它不会闪烁。

The flashing is not caused by the timer per se. The UIButton method setTitle:forState causes the flashing. One simple work around is to use a UIButton with no title and to superimpose a UILabel. When you change the UILabel text, it will not flash.

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