如何使用单次触摸更改UISlider值？

Question

我正在开发我的第一个iOS应用程序,其中包含一个UISlider.我知道如何在UISlider拖动时获取值.但对于我的应用程序,我需要一键式获取滑块的值; 即如果我触摸某处UISlider,UILabel则应显示其正确值.

这样可能吗？任何教程或代码都非常有用.

Answer 1

请写下面的代码可能对您有所帮助:)

这里tapCount是int在.h文件中声明的变量

- (void)viewDidLoad
{
  tapCount = 0; // Count tap on Slider 

 UITapGestureRecognizer *gr = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(sliderTapped:)];
    [slider addGestureRecognizer:gr];

}

 - (void)sliderTapped:(UIGestureRecognizer *)g 
    {
/////////////// For TapCount////////////

        tapCount = tapCount + 1;
        NSLog(@"Tap Count -- %d",tapCount);

/////////////// For TapCount////////////

        UISlider* s = (UISlider*)g.view;
        if (s.highlighted)
            return; // tap on thumb, let slider deal with it
        CGPoint pt = [g locationInView: s];
        CGFloat percentage = pt.x / s.bounds.size.width;
        CGFloat delta = percentage * (s.maximumValue - s.minimumValue);
        CGFloat value = s.minimumValue + delta;
        [s setValue:value animated:YES];

        NSString *str=[NSString stringWithFormat:@"%.f",[self.slider value]];
        self.lbl.text=str;
    }

对于Swift用户

override func viewDidLoad()
{
    super.viewDidLoad()

    tapCount = 0
    let gr = UITapGestureRecognizer(target: self, action: #selector(self.sliderTapped(_:)))
    slider.addGestureRecognizer(gr)

}

func sliderTapped(_ g: UIGestureRecognizer) {

    /////////////// For TapCount////////////
    tapCount = tapCount + 1
    print("Tap Count -- \(tapCount)")
    /////////////// For TapCount////////////

    let s: UISlider? = (g.view as? UISlider)
    if (s?.isHighlighted)! {
        return
    }

    // tap on thumb, let slider deal with it
    let pt: CGPoint = g.location(in: s)
    let percentage = pt.x / (s?.bounds.size.width)!
    let delta = Float(percentage) * Float((s?.maximumValue)! - (s?.minimumValue)!)
    let value = (s?.minimumValue)! + delta
    s?.setValue(Float(value), animated: true)
    let str = String(format: "%.f", slider.value)
    lbl.text = str
}

Answer 2

更正@ipatel:先前答案中的数学不完整,并且由于缺少拇指宽度考虑而导致抖动.

如果您选择子类,它应该是什么样子UISlider:

- (BOOL)beginTrackingWithTouch:(UITouch *)touch withEvent:(UIEvent *)event
{
    [super beginTrackingWithTouch:touch withEvent:event];
    CGPoint touchLocation = [touch locationInView:self];
    CGFloat value = self.minimumValue + (self.maximumValue - self.minimumValue) *
        ((touchLocation.x - self.currentThumbImage.size.width/2) /
        (self.frame.size.width-self.currentThumbImage.size.width));
    [self setValue:value animated:YES];

    return YES;
}