滑块值未显示在我的 imageView 中？答案

【问题标题】：Slider value is not showing up in my imageView?滑块值未显示在我的 imageView 中？
【发布时间】：2011-04-20 17:17:52
【问题描述】：

我有一个 Slider 并想在一个 Image 视图中显示它的值，该视图与滑块的拇指接触。我添加了 ImageView 和标签以在 UIView 中显示值并使其随着滑块拇指的移动而移动。但由于某种原因，它没有显示滑块的值，尽管我检查了我们收到的值。

-(void)addSliderX:frame andminimumValue:(int)min andmaximumValue:(int)max andSliderValue:(int)value{
    CGRect frame1 = CGRectFromString(frame);
    statSlider = [[UISlider alloc]initWithFrame:frame1];
    [statSlider setMinimumTrackImage:[[UIImage imageNamed:@"greenSlider.png"] stretchableImageWithLeftCapWidth:10.0 topCapHeight:10.0] forState:UIControlStateNormal]; 
    [statSlider setThumbImage:[UIImage imageNamed:@"sliderBar_greenThumb.png"] forState:UIControlStateNormal];
    [statSlider setMinimumValue:min];
    [statSlider setMaximumValue:max];
    statSlider.continuous = YES;
    positionX = value;
    [statSlider addTarget:self action:@selector(valueChanged:) forControlEvents:UIControlEventValueChanged];
    [statSlider addTarget:self action:@selector(sliderChanged:) forControlEvents:UIControlEventTouchUpInside];
    UIView * bubble = [[UIView alloc]init];
    UIImageView * back = [[UIImageView alloc]initWithImage:[UIImage imageNamed:@"sliderBar_handle_number.png"]];
    UILabel * val = [[UILabel alloc]init];
    bubble.tag = 1;
    back.tag = 2;
    val.tag = 3; 
    bubble.alpha = 0;
    back.alpha = 0;
    val.alpha = 0;

    [self.view addSubview:statSlider]; 
    [self.view addSubview:bubble];
    [bubble addSubview:back];
    [bubble addSubview:val];

}

-(void)valueChanged:(id)sender{

    UISlider *localSlider = (UISlider *)sender;
    greenSliderValue = [[NSString alloc] initWithString:[NSString stringWithFormat:@"%3.0f", [localSlider value]]];
    dsp =[greenSliderValue floatValue];
    UIView * bubble = (UIView*)[self.view viewWithTag:1];
    UIImageView * back = (UIImageView*)[bubble viewWithTag:2];
    UILabel * val = (UILabel*)[bubble viewWithTag:3]; 
    val.text = [[NSString alloc] initWithString:[NSString stringWithFormat:@"%3.0f", [localSlider value]]];

    [val setText:[NSString stringWithFormat:@"%3.0f", [localSlider value]]];
    UIFont * font  = YEAR_LABEL_FONT;
    val.font = font;
    val.textColor = DESC_Color_White;
    bubble.alpha = 1;
    back.alpha = 1;
    val.alpha = 1;


    CGFloat sliderMax = localSlider.maximumValue;
    CGFloat sliderMin = localSlider.minimumValue;

    CGFloat sliderMaxMinDiff = sliderMax - sliderMin;
    CGFloat sliderValue = dsp;
    CGFloat xCoord = 65.0-42.0;
    CGFloat yCoord = (CGFloat)positionX;
    CGFloat halfMax = (sliderMax+sliderMin)/2.0;

    if (sliderValue > halfMax) 
    {
        xCoord = xCoord-(sliderValue-halfMax);
    }
    else 
    {
        xCoord = xCoord + (halfMax-sliderValue);
    }

    xCoord= xCoord + (600/sliderMaxMinDiff)*(sliderValue-sliderMin);
    back.frame = CGRectMake(xCoord,yCoord,84,47);

}

【问题讨论】：

标签： iphone uiview uislider

【解决方案1】：

您设置了两次文本，但我猜这只是您调试问题的一部分，对吧？

这两行是多余的：

 val.text = [[NSString alloc] initWithString:[NSString stringWithFormat:@"%3.0f", [localSlider value]]];
[val setText:[NSString stringWithFormat:@"%3.0f", [localSlider value]]];

尝试将日志放在那里进行测试，将上面的两个替换为：

NSString *valString = [NSString stringWithFormat:@"%3.0f", [localSlider value]];
[val setText:valString];
NSLog(@"val: %@, valString: %@", val, valString);

我的猜测是 val 会在那里显示为 nil。

【讨论】：