label中的文字类似跑马灯的效果

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label中的文字类似跑马灯的效果

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一行中的文字实现在固定的区域跑马灯效果！

h文件：

#import <UIKit/UIKit.h>

@interface MyLabel : UIViewController {

UILabel *label;

UILabel *big;

}

@property (nonatomic, retain) UILabel *label;

@property (nonatomic, retain) UILabel *big;

-(id)initWithMyFrame:(CGRect)frame;

-(void)startAnimation:(NSString *)string;

@end

m文件：

#import "MyLabel.h"

@implementation MyLabel

@synthesize label,big;

-(id)initWithMyFrame:(CGRect)frame

{

self = [super init];

if(self)

{

self.view = [[UIView alloc] initWithFrame:frame];

}

label = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, frame.size.width, frame.size.height)];

big = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, frame.size.width, frame.size.height)];

[self.view insertSubview:big atIndex:0];

[big setBackgroundColor:[UIColor clearColor]];

[big setTextColor:[UIColor whiteColor]];

[self.view setBackgroundColor:[UIColor clearColor]];

[self.view setClipsToBounds:YES];//移动到view外面的不显示

return self;

}

-(void)startAnimation:(NSString *)string

{

int length = [string length];

CGRect labFrame = self.label.frame;

CGSize labSize = labFrame.size;

UIFont *font = [UIFont fontWithName:@"Georgia-Bold" size:17];

[big setFont:font];

if(length * 17 < labSize.width)

{

[big.layer removeAnimationForKey:@"animateLayer"];

big.frame = CGRectMake(0, 0, length*17, self.label.frame.size.height);

big.text = string;

//[CATransaction commit];//如果这里再次提交，就把anmiation给取消掉了，因为frame重设，removeanimation了。

}

else

{

big.text = string;

big.frame = CGRectMake(self.label.frame.size.width, 0, length*17, self.label.frame.size.height);

//[CATransaction commit];//如果在这里提交会覆盖上一个animation的效果

CABasicAnimation *theAnimation;

theAnimation=[CABasicAnimation animationWithKeyPath:@"transform.translation.x"];

theAnimation.duration=3;

theAnimation.repeatCount=999999;

theAnimation.autoreverses=NO;

theAnimation.toValue=[NSNumber numberWithFloat:-length*17-self.label.frame.size.width];

[big.layer addAnimation:theAnimation forKey:@"animateLayer"];

}

- (void)dealloc {

[big release];

[label release];

[super dealloc];

}

@end

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