Ios 将滑块的位置更改为取消

我正在按照我的项目要求使用，但我找不到如何更改按钮的位置

我已经通读了所有的代码，但无法理解。 以下是主要代码：

进口

#导入“SlideToCancelViewController.h”
@接口SlideToCancelViewController（）
-（void）setGradientLocations：（CGFloat）leftEdge；
-（无效）startTimer；
-（无效）停止计时器；
@结束
静态常数CGFloat梯度宽度=0.2；
静态常数CGFloat梯度dimalpha=0.5；
静态常量int animationFramesPerSec=8；
@实现SlideToCancelViewController
@综合代表；
//实现“enabled”属性
-（BOOL）已启用{
返回滑块。已启用；
}
-（void）setEnabled：（BOOL）enabled{
slider.enabled=已启用；
label.enabled=已启用；
如果（已启用）{
slider.value=0.0；
label.alpha=1.0；
touchIsDown=否；
[自我启动者]；
}否则{
[自动停止计时器]；
}
}
-（UILabel*）标签{
//访问视图，这将强制调用loadView
//如果尚未创建标签，将创建哪个标签
（无效）[自我观点]；
退货标签；
}
//实现loadView以编程方式创建视图层次结构，而不使用nib。
-（void）负荷视图{
//加载轨迹背景
UIImage*trackImage=[UIImage ImageName:@“sliderTrack.png”]；
sliderBackground=[[UIImageView alloc]initWithImage:trackImage]；
//创建与“轨迹回溯”大小相同的superview，并将背景图像添加到其中
UIView*view=[[UIView alloc]initWithFrame:sliderBackground.frame]；
[视图添加子视图：滑块背景]；
//添加滑块，使其具有位于轨迹中心的正确几何图形
slider=[[UISlider alloc]initWithFrame:sliderBackground.frame]；
CGRect sliderFrame=slider.frame；
sliderFrame.size.width-=46；//轨迹的每个“边”都有23像素宽
slider.frame=sliderFrame；
slider.center=sliderBackground.center；
slider.backgroundColor=[UIColor clearColor]；
[slider setMinimumTrackImage:[UIImage ImageName:@“sliderMaxMin-02.png”]用于状态：UIControlStateNormal]；
[slider setMaximumTrackImage:[UIImage ImageName:@“sliderMaxMin-02.png”]用于状态：UIControlStateNormal]；
UIImage*thumbImage=[UIImage ImageName:@“sliderThumb.png”]；
[滑块设置thumbImage:thumbImage for状态：uicontrol状态正常]；
slider.minimumValue=0.0；
slider.maximumValue=1.0；
slider.continuous=是；
slider.value=0.0；
//设置滑块动作方法
[目标：自我
操作：@选择器（幻灯片：）
forControlEvents:UIControlEventTouchUpInside]；
[目标：自我
操作：@选择器（滑块下降：）
forControlEvents:UIControlEventTouchDown]；
[目标：自我
操作：@选择器（滑块更改：）
forControlEvents:UIControlEventValueChanged]；
//使用文本所需的实际大小创建标签
//如果使用“标签”属性更改文本、字体或字体大小，
//您可能需要重新计算标签的边框。
NSString*labelText=NSLocalizedString（@“幻灯片取消”，“幻灯片取消标签”）；
UIFont*labelFont=[UIFont systemFontOfSize:24]；
CGSize labelSize=[labelText sizeWithFont:labelFont]；
label=[[UILabel alloc]initWithFrame:CGRectMake（0.0,0.0，labelSize.width，labelSize.height）]；
//将标签居中放置在轨迹的可滑动部分上
CGFloat labelHorizontalCenter=slider.center.x+（thumbImage.size.width/2）；
label.center=CGPointMake（labelHorizontalCenter，slider.center.y）；
//设置其他标签属性并将其添加到视图中
label.textColor=[UIColor-whiteColor]；
label.textAlignment=UITextAlignmentCenter；
label.backgroundColor=[UIColor clearColor]；
label.font=labelFont；
label.text=labelText；
[视图添加子视图：标签]；
[视图添加子视图：滑块]；
//此属性在创建时设置为“否”（已禁用）。
//调用者必须将其设置为“是”才能设置滑块动画。
//当视图不可见时，应按顺序将其设置为“否”（禁用）
//关闭计时器并节省CPU资源。
self.enabled=否；
//使用中的自定义绘图代码渲染标签文本动画
//标签的图层。
label.layer.delegate=self；
//将视图控制器的视图属性设置为上述所有属性
self.view=视图；
//视图由超类保留，因此发布我们的副本
[查看发布]；
}
-（无效）未收到记忆警告{
//如果视图没有superview，则释放该视图。
[超级记忆警告]；
//释放所有未使用的缓存数据、图像等。
}
-（无效）视图卸载{
//释放主视图的所有保留子视图。
[自动停止计时器]；
[滑块背景释放]，滑块背景=零；
[滑块释放]，滑块=零；
[标签发布]，标签=无；
}
//UISlider作用
-（void）sliderUp:（UISlider*）发送器
{
//过滤掉重复的sliderUp事件
如果（touchIsDown）{
touchIsDown=否；
if（slider.value！=1.0）//如果该值不是最大值，则将该坏小子滑回零
{
[滑块设置值：0动画：是]；
label.alpha=1.0；
[自我启动者]；
}
否则{
//告诉delagate我们一直滑到了右边
[代表取消]；
}
}
}
-（void）sliderDown:（UISlider*）发送器
{
touchIsDown=是；
}
-（void）滑块更改：（UISlider*）发送器
{
//随着滑块向右移动，文本淡入淡出。此代码使
//当滑块向右移动35%时，文本完全消失。
label.alpha=最大值（0.0,1.0-（slider.value*3.5））；
//如果滑块移离零点，则停止动画
如果（slider.value！=0）{
[自动停止计时器]；
[label.layer setNeedsDisplay]；
}
}
//动画计时器方法
-（空）动画
#import "SlideToCancelViewController.h"

@interface SlideToCancelViewController()

- (void) setGradientLocations:(CGFloat)leftEdge;
- (void) startTimer;
- (void) stopTimer;

@end

static const CGFloat gradientWidth = 0.2;
static const CGFloat gradientDimAlpha = 0.5;
static const int animationFramesPerSec = 8;

@implementation SlideToCancelViewController

@synthesize delegate;

// Implement the "enabled" property
- (BOOL) enabled {
    return slider.enabled;
}

- (void) setEnabled:(BOOL)enabled{
    slider.enabled = enabled;
    label.enabled = enabled;
    if (enabled) {
        slider.value = 0.0;
        label.alpha = 1.0;
        touchIsDown = NO;
        [self startTimer];
    } else {
        [self stopTimer];
    }
}

- (UILabel *)label {
    // Access the view, which will force loadView to be called 
    // if it hasn't already been, which will create the label
    (void)[self view];

    return label;
}

// Implement loadView to create a view hierarchy programmatically, without using a nib.
- (void)loadView {
    // Load the track background
    UIImage *trackImage = [UIImage imageNamed:@"sliderTrack.png"];
    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];

    // Add the slider with correct geometry centered over the track
    slider = [[UISlider alloc] initWithFrame:sliderBackground.frame];
    CGRect sliderFrame = slider.frame;
    sliderFrame.size.width -= 46; //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:@"sliderThumb.png"];
    [slider setThumbImage:thumbImage forState:UIControlStateNormal];
    slider.minimumValue = 0.0;
    slider.maximumValue = 1.0;
    slider.continuous = YES;
    slider.value = 0.0;

    // 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(@"slide to cancel", @"SlideToCancel label");
    UIFont *labelFont = [UIFont systemFontOfSize:24];
    CGSize labelSize = [labelText sizeWithFont:labelFont];
    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 whiteColor];
    label.textAlignment = UITextAlignmentCenter;
    label.backgroundColor = [UIColor clearColor];
    label.font = labelFont;
    label.text = labelText;
    [view addSubview:label];

    [view addSubview:slider];

    // This property is set to NO (disabled) on creation.
    // The caller must set it to YES to animate the slider.
    // It should be set to NO (disabled) when the view is not visible, in order
    // to turn off the timer and conserve CPU resources.
    self.enabled = NO;

    // Render the label text animation using our custom drawing code in
    // the label's layer.
    label.layer.delegate = self;

    // Set the view controller's view property to all of the above
    self.view = view;

    // The view is retained by the superclass, so release our copy
    [view release];
}

- (void)didReceiveMemoryWarning {
    // Releases the view if it doesn't have a superview.
    [super didReceiveMemoryWarning];

    // Release any cached data, images, etc that aren't in use.
}

- (void)viewDidUnload {
    // Release any retained subviews of the main view.
    [self stopTimer];
    [sliderBackground release], sliderBackground = nil;
    [slider release], slider = nil;
    [label release], label = nil;
}

// UISlider actions
- (void) sliderUp: (UISlider *) sender
{
    //filter out duplicate sliderUp events
    if (touchIsDown) {
        touchIsDown = NO;

        if (slider.value != 1.0)  //if the value is not the max, slide this bad boy back to zero
        {
            [slider setValue: 0 animated: YES];
            label.alpha = 1.0;
            [self startTimer];
        }
        else {
            //tell the delagate we are slid all the way to the right
            [delegate cancelled];
        }
    }
}

- (void) sliderDown: (UISlider *) sender
{
    touchIsDown = YES;
}

- (void) sliderChanged: (UISlider *) sender
{
    // Fade the text as the slider moves to the right. This code makes the
    // text totally dissapear when the slider is 35% of the way to the right.
    label.alpha = MAX(0.0, 1.0 - (slider.value * 3.5));

    // Stop the animation if the slider moved off the zero point
    if (slider.value != 0) {
        [self stopTimer];
        [label.layer setNeedsDisplay];
    }
}

// animationTimer methods
- (void)animationTimerFired:(NSTimer*)theTimer {
    // Let the timer run for 2 * FPS rate before resetting.
    // This gives one second of sliding the highlight off to the right, plus one
    // additional second of uniform dimness
    if (++animationTimerCount == (2 * animationFramesPerSec)) {
        animationTimerCount = 0;
    }

    // Update the gradient for the next frame
    [self setGradientLocations:((CGFloat)animationTimerCount/(CGFloat)animationFramesPerSec)];
}

- (void) startTimer {
    if (!animationTimer) {
        animationTimerCount = 0;
        [self setGradientLocations:0];
        animationTimer = [[NSTimer 
                           scheduledTimerWithTimeInterval:1.0/animationFramesPerSec 
                           target:self 
                           selector:@selector(animationTimerFired:) 
                           userInfo:nil 
                           repeats:YES] retain];
    }
}

- (void) stopTimer {
    if (animationTimer) {
        [animationTimer invalidate];
        [animationTimer release], animationTimer = nil;
    }
}

// label's layer delegate method
- (void)drawLayer:(CALayer *)theLayer
        inContext:(CGContextRef)theContext
{
    // Set the font
    const char *labelFontName = [label.font.fontName UTF8String];

    // Note: due to use of kCGEncodingMacRoman, this code only works with Roman alphabets! 
    // In order to support non-Roman alphabets, you need to add code generate glyphs,
    // and use CGContextShowGlyphsAtPoint
    CGContextSelectFont(theContext, labelFontName, label.font.pointSize, kCGEncodingMacRoman);

    // Set Text Matrix
    CGAffineTransform xform = CGAffineTransformMake(1.0,  0.0,
                                                    0.0, -1.0,
                                                    0.0,  0.0);
    CGContextSetTextMatrix(theContext, xform);

    // Set Drawing Mode to clipping path, to clip the gradient created below
    CGContextSetTextDrawingMode (theContext, kCGTextClip);

    // Draw the label's text
    const char *text = [label.text cStringUsingEncoding:NSMacOSRomanStringEncoding];
    CGContextShowTextAtPoint(
        theContext, 
        0, 
        (size_t)label.font.ascender,
        text, 
        strlen(text));

    // Calculate text width
    CGPoint textEnd = CGContextGetTextPosition(theContext);

    // Get the foreground text color from the UILabel.
    // Note: UIColor color space may be either monochrome or RGB.
    // If monochrome, there are 2 components, including alpha.
    // If RGB, there are 4 components, including alpha.
    CGColorRef textColor = label.textColor.CGColor;
    const CGFloat *components = CGColorGetComponents(textColor);
    size_t numberOfComponents = CGColorGetNumberOfComponents(textColor);
    BOOL isRGB = (numberOfComponents == 4);
    CGFloat red = components[0];
    CGFloat green = isRGB ? components[1] : components[0];
    CGFloat blue = isRGB ? components[2] : components[0];
    CGFloat alpha = isRGB ? components[3] : components[1];

    // The gradient has 4 sections, whose relative positions are defined by
    // the "gradientLocations" array:
    // 1) from 0.0 to gradientLocations[0] (dim)
    // 2) from gradientLocations[0] to gradientLocations[1] (increasing brightness)
    // 3) from gradientLocations[1] to gradientLocations[2] (decreasing brightness)
    // 4) from gradientLocations[3] to 1.0 (dim)
    size_t num_locations = 3;

    // The gradientComponents array is a 4 x 3 matrix. Each row of the matrix
    // defines the R, G, B, and alpha values to be used by the corresponding
    // element of the gradientLocations array
    CGFloat gradientComponents[12];
    for (int row = 0; row < num_locations; row++) {
        int index = 4 * row;
        gradientComponents[index++] = red;
        gradientComponents[index++] = green;
        gradientComponents[index++] = blue;
        gradientComponents[index] = alpha * gradientDimAlpha;
    }

    // If animating, set the center of the gradient to be bright (maximum alpha)
    // Otherwise it stays dim (as set above) leaving the text at uniform
    // dim brightness
    if (animationTimer) {
        gradientComponents[7] = alpha;
    }

    // Load RGB Colorspace
    CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceRGB();

    // Create Gradient
    CGGradientRef gradient = CGGradientCreateWithColorComponents (colorspace, gradientComponents,
                                                                  gradientLocations, num_locations);
    // Draw the gradient (using label text as the clipping path)
    CGContextDrawLinearGradient (theContext, gradient, label.bounds.origin, textEnd, 0);

    // Cleanup
    CGGradientRelease(gradient);
    CGColorSpaceRelease(colorspace);
}

- (void) setGradientLocations:(CGFloat) leftEdge {
    // Subtract the gradient width to start the animation with the brightest 
    // part (center) of the gradient at left edge of the label text
    leftEdge -= gradientWidth;

    //position the bright segment of the gradient, keeping all segments within the range 0..1
    gradientLocations[0] = leftEdge < 0.0 ? 0.0 : (leftEdge > 1.0 ? 1.0 : leftEdge);
    gradientLocations[1] = MIN(leftEdge + gradientWidth, 1.0);
    gradientLocations[2] = MIN(gradientLocations[1] + gradientWidth, 1.0);

    // Re-render the label text
    [label.layer setNeedsDisplay];
}

- (void)dealloc {
    [self stopTimer];
    [self viewDidUnload];
    [super dealloc];
}

@end