需要帮助配置 NSTimer 和 UIButton

Question

我有以下秒表功能的代码。

我有 2 个 UIButton。一个用于启动/停止，另一个用于重置。

我想将这 2 个按钮组合成 1 个按钮，用作启动按钮，然后在计时器运行时，它将成为停止按钮，按下时会重置计时器。

我如何修改此代码以反映这一点？

- (IBAction)startStop:(UIButton *)sender 
{
    if ( self.myTimer ) 
    {
        [self.myTimer invalidate];
        self.myTimer = nil;

        [sender setTitle:@"Start" forState:UIControlStateNormal];
    } 
    else 
    {
        self.myTimer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(handleTimer:) userInfo:nil repeats:YES];
        [sender setTitle:@"Stop" forState:UIControlStateNormal];
    }
}

- (void)handleTimer:(NSTimer *)timer 
{
    self.counter--;
    self.timerLabel.text = [NSString stringWithFormat:@"%ld", self.counter];

    if ( self.counter <= 0 )
    {
        AudioServicesPlaySystemSound(kSystemSoundID_Vibrate);
        [self.myTimer invalidate];
        self.myTimer = nil;
        self.timerButton.enabled = NO;
    }
}

- (IBAction)reset:(id)sender 
{
    self.timerButton.enabled = YES;
    self.counter = self.counterSegment;
    self.timerLabel.text = timerCount;
    self.timerButton.titleLabel.text = @"Start";
    self.timerButton.titleLabel.adjustsFontSizeToFitWidth = YES;
}
- (void)segmentedControl:(SVSegmentedControl*)segmentedControl didSelectIndex:(NSUInteger)index
{
    if ( self.myTimer ) 
    {
        [self.myTimer invalidate];
        self.myTimer = nil;
        self.timerButton.titleLabel.text = @"Start";
        self.timerButton.titleLabel.adjustsFontSizeToFitWidth = YES;
    }   
    else
    {
        self.timerButton.enabled = YES;
        self.counter = self.counterSegment;
        self.timerLabel.text = timerCount;
        self.timerButton.titleLabel.text = @"Start";
        self.timerButton.titleLabel.adjustsFontSizeToFitWidth = YES;
    }
    if (index == 0)
    {
        NSLog(@"15 sec");
        self.timerCount = @"15";
        self.counterSegment = 15;
    }
    else if (index == 1)
    {
        NSLog(@"30 sec");
        self.timerCount = @"30";
        self.counterSegment = 30;
    }
}

Answer 1

您可以执行的步骤：

1. 从用户界面中删除重置按钮；

2. 修改 startStop 方法，以便在计时器已运行时按下该方法，它将向自身发送 reset 消息：

我认为这应该足够了。看一下这段代码：

- (IBAction)startStop:(UIButton *)sender 
{
if ( self.myTimer ) 
{
    [self.myTimer invalidate];
    self.myTimer = nil;

    [self reset:sender];   //-- LINE ADDED

    [sender setTitle:@"Start" forState:UIControlStateNormal];
} 
else 
{
    self.myTimer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(handleTimer:) userInfo:nil repeats:YES];
    [sender setTitle:@"Stop" forState:UIControlStateNormal];
}
}

由于在 reset 中您没有使用 sender 参数，因此您可以将其删除并具有：

- (void)reset
{
self.timerButton.enabled = YES;
self.counter = self.counterSegment;
self.timerLabel.text = timerCount;
self.timerButton.titleLabel.text = @"Start";
self.timerButton.titleLabel.adjustsFontSizeToFitWidth = YES;
}

这样您将能够使用此方法以更通用的方式。