objective-c - 根据标签设置UIImage

我正在研究一个脚本，该脚本循环遍历按数字顺序设置并由标签选择的LED UIImageView数组。根据步骤(aka数字)的不同，LED图像上的指示灯将显示为开或关。此方法的主要目标是采取当前步骤并显示“LED亮”图像，同时将其减去1，然后显示上一步的“LED灭”图像。因此，一次只能点亮一个LED。

不幸的是，我只能使“LED亮”图像正确显示。该序列中的所有LED均点亮，但它们从未熄灭。我的第一个猜测是我没有以正确的方式减去NSInterger。但是，当我检查日志时，一切都应该在原处。如果当前步骤是2，则上一步是1。不知道为什么它不起作用。谢谢!

sequencerLocation和previousLocation都设置为属性。

- (void)clockLoop:(UInt8)seqClockPulse
{
//cast to an int to use in loop
NSInteger stepCount = sequencerSteps;

//increment sequencer on pulse in
sequencerLocation++;

if(sequencerLocation > stepCount)
{
    sequencerLocation = 1;
}

//setup previous step location
previousLocation = (sequencerLocation - 1);

if (previousLocation == 0)
{
    previousLocation = stepCount;
}

//change led color in led array
for (UIImageView *led in sequencerLEDArray)
{
    if(led.tag == sequencerLocation)
    {
        UIImageView *previousLed = (UIImageView *)[led viewWithTag:previousLocation];
        [previousLed setImage:[UIImage imageNamed:@"images/seq_LED_off.png"]];
        NSLog(@"Previous: %d", previousLocation);

        UIImageView *currentLed = (UIImageView *)[led viewWithTag:sequencerLocation];
        [currentLed setImage:[UIImage imageNamed:@"images/seq_LED_on.png"]];
        NSLog(@"Current: %d", sequencerLocation);
    }
}

}

最佳答案

//change led color in led array
for (UIImageView *led in sequencerLEDArray)
{
if(led.tag == sequencerLocation)
{
    //  I THINK the problem is here
  //  UIImageView *previousLed = (UIImageView *)[led viewWithTag:previousLocation];
    //  TRY THIS instead
    UIImageView *previousLed = [led.superview viewWithTag:previousLocation];
    [previousLed setImage:[UIImage imageNamed:@"images/seq_LED_off.png"]];
    NSLog(@"Previous: %d", previousLocation);

    // HERE you don't need to search for the tag you already tested for it in your if statement
    UIImageView *currentLed = (UIImageView *)[led viewWithTag:sequencerLocation];
    [currentLed setImage:[UIImage imageNamed:@"images/seq_LED_on.png"]];
    NSLog(@"Current: %d", sequencerLocation);
}
}

viewWithTag:
Discussion

此方法在当前视图及其所有子视图中搜索指定的视图。

因此，当您通过自身的标签搜索led时，它会自动返回，但是当您搜索其兄弟时却找不到它，这就是为什么我建议将led.superview作为搜索标签的地方的原因，父级应该能够找另一个孩子

关于objective-c - 根据标签设置UIImage，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/8737097/