Как центрировать UISlider в UIView?

Question

Я пытаюсь центрировать UISlider внутри UIView, но он продолжает выстраиваться в линию слева? Вот код.

 // Implement loadView to create a view hierarchy programmatically, without using a nib. 
    - (UIView *)manufactorSliderWithLabel:(NSString *)sliderText 
             url:(NSString *)urlPath 
           callback:(NSString *)method 
            message:(NSString *)message 
            status:(NSString *)status { 

     // Load the track background 
     UIImage *trackImage = [UIImage imageNamed:@"sliderTrack.png"]; 
     UIImageView *sliderBackground = [[UIImageView alloc] initWithImage:trackImage]; 

     // Create the superview same size as track backround, and add the background image to it 
     UIView *view = [[UIView alloc] initWithFrame:sliderBackground.frame]; 
     [view addSubview:sliderBackground]; 
     view.backgroundColor = [UIColor redColor]; 

     // Add the slider with correct geometry centered over the track 
     UISlider* slider = [[UISlider alloc] initWithFrame:sliderBackground.frame]; 
     CGRect sliderFrame = slider.frame; 
     sliderFrame.size.width -= 3; //each "edge" of the track is 23 pixels wide 
     slider.frame = sliderFrame; 
     slider.center = sliderBackground.center; 
     slider.backgroundColor = [UIColor clearColor]; 
     [slider setMinimumTrackImage:[UIImage imageNamed:@"sliderMaxMin-02.png"] forState:UIControlStateNormal]; 
     [slider setMaximumTrackImage:[UIImage imageNamed:@"sliderMaxMin-02.png"] forState:UIControlStateNormal]; 
     UIImage *thumbImage = [UIImage imageNamed:@"sliderThumbGreen_normal.png"]; 
     [slider setThumbImage:thumbImage forState:UIControlStateNormal]; 
     slider.minimumValue = 0.0; 
     slider.maximumValue = 1.0; 
     slider.continuous = YES; 
     slider.value = 0.0; 

     slider.url = urlPath; 
     slider.message = message; 
     slider.socketStatus = status; 
     slider.callbackMethod = method; 


     // Set the slider action methods 
     [slider addTarget:self 
        action:@selector(sliderUp:) 
     forControlEvents:UIControlEventTouchUpInside]; 
     [slider addTarget:self 
        action:@selector(sliderDown:) 
     forControlEvents:UIControlEventTouchDown]; 
     [slider addTarget:self 
        action:@selector(sliderChanged:) 
     forControlEvents:UIControlEventValueChanged]; 

     // Create the label with the actual size required by the text 
     // If you change the text, font, or font size by using the "label" property, 
     // you may need to recalculate the label's frame. 
     NSString *labelText = NSLocalizedString(sliderText, @"SlideToCancel label"); 
     UIFont *labelFont = [UIFont systemFontOfSize:12]; 
     CGSize labelSize = [labelText sizeWithFont:labelFont]; 
     UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(0.0, 0.0, labelSize.width, labelSize.height)]; 

     // Center the label over the slidable portion of the track 
     CGFloat labelHorizontalCenter = slider.center.x + (thumbImage.size.width/2); 
     label.center = CGPointMake(labelHorizontalCenter, slider.center.y); 

     // Set other label attributes and add it to the view 
     label.textColor = [UIColor blackColor]; 
     label.textAlignment = UITextAlignmentCenter; 
     label.backgroundColor = [UIColor clearColor]; 
     label.font = labelFont; 
     label.text = labelText; 
     [view addSubview:label]; 

     slider.backgroundColor = [UIColor greenColor]; 

     [view addSubview:slider]; 



     return view; 

    } 

Answer 1

Если Вы хотите отцентрировать ползунок соответствующего для sliderBackground, тогда первый набор кадра sliderBackground, потому что в вашем коде я вижу, что вы не ставите рамку sliderBackground, затем выполнить

slider.center = sliderBackground.center;