我根据项目的要求使用SlideToCancel，但我无法找到如何更改按钮的位置。
我已经完成了所有代码但无法计算。 这是主要代码：
#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
很抱歉发布繁重的代码。
P.S。：我知道AppStore不接受这个代码，但我有兴趣学习＆amp;在QuartzCore图形上做的比使用界面构建器更多。
答案 0 :(得分：0)
检查此答案https://stackoverflow.com/a/25894355/1344237
您必须删除label.layer.delegate = self;