iOS 字体滚动效果 ScrollLabel

写了一个简单的字体滚动效果。

用了一种取巧的方式，传入两个一摸一样的Label（当然也可以是别的视图）, 话不多说，代码里面讲解。

SEScrollLabel.h

#import <UIKit/UIKit.h>

/*! @brief 回调代码块

*

* 当滚动效果持续loopsDone次之后，isFinished值会变为YES，执行代码块

* @param loopsDone 滚动效果执行次数

* @param isFinished 是否已经结束

*/

typedef void (^PMAnimationFinished)(NSUInteger loopsDone, BOOL isFinished);

enum {

PMScrollDirectionFromLeft                   = 0,    // Animation starts from left and continues to the right side

PMScrollDirectionFromRight                  = 1     // Animation starts from right and continues back to the left side

}; typedef NSUInteger PMScrollDirection;

@interface SEScrollLabel : UIScrollView

/*!

*

* @param frame 滚动视图的frame

* @param labels 存放UILabel数组，这个demo目前最多支持两个

* @param scrollDirection 滚动方向

* @param scrollSpeed 滚动速度，单位是 CGFloat/s

* @param loops 滚动执行次数

* @param completition 执行结束调用方法

* @return 返回SEScrollLabel对象

*/

-(instancetype)initWithFrame:(CGRect) frame labels:(NSArray *)labels

direction:(PMScrollDirection) scrollDirection

speed:(CGFloat) scrollSpeed

loops:(NSUInteger) loops

completition:(PMAnimationFinished) completition;

-(void)setText:(NSString *)text;

- (void) beginAnimation;

-(void)resetAnimation;

@end

SEScrollLabel.m

#import "SEScrollLabel.h"

#define LABEL_SPACING 30   //定义了字体滚动的间隙

@interface SEScrollLabel()

@property (nonatomic, assign) BOOL needAnimating; //是否需要滚动，label长度大于scrollLabel长度，设为YES，否则为NO

@property (nonatomic, assign) BOOL isAnimating;      //是否正在滚动

@property (nonatomic, assign) CGFloat scrollSpeed;   //滚动速度

@property (nonatomic, assign) NSInteger numberOfLoops; //滚动循环次数

@property (nonatomic, assign) NSInteger runningLoops;   //当前已经执行过的滚动次数

@property (nonatomic, assign) PMScrollDirection scrollDirection;  //滚动方向

@property (nonatomic, strong) PMAnimationFinished finishedBlock; //回调代码块

@end

@implementation SEScrollLabel

-(instancetype)initWithFrame:(CGRect) frame labels:(NSArray *)labels

direction:(PMScrollDirection) scrollDirection

speed:(CGFloat) scrollSpeed

loops:(NSUInteger) loops

completition:(PMAnimationFinished) completition

{

self = [super initWithFrame:frame];

if (self != nil)

{

UILabel *label = [labels firstObject];

CGRect labelFrame = label.frame;

if (label.frame.size.width <= frame.size.width) //如果第一个label宽度小于视图宽度，则判断不需要滚动显示

{

self.contentSize = CGSizeMake(labelFrame.size.width , labelFrame.size.height);

labelFrame.origin.x = frame.size.width - labelFrame.size.width;

labelFrame.origin.y = 0;

label.frame = labelFrame;

[self addSubview:label];

_needAnimating = NO;

}

else

{

self.contentSize = CGSizeMake(labelFrame.size.width *2 + LABEL_SPACING *2 , labelFrame.size.height);

labelFrame.origin.x = 0;

labelFrame.origin.y = 0;

label.frame = labelFrame;

[self addSubview:label];

if (scrollDirection == PMScrollDirectionFromRight)

{

labelFrame.origin.x += LABEL_SPACING + labelFrame.size.width;

}

else if (scrollDirection == PMScrollDirectionFromLeft)

{

labelFrame.origin.x -= LABEL_SPACING + labelFrame.size.width;

}

UILabel *sameLabel = [labels lastObject];

sameLabel.frame = labelFrame;

[self addSubview:sameLabel];

self.scrollDirection = scrollDirection;

self.scrollSpeed = scrollSpeed;

self.numberOfLoops = loops;

self.finishedBlock = completition;

self.needAnimating = YES;

}

}

return self;

}

- (void) beginAnimation

{

　　//所做的动画非常简单，就是让scrollView的conentOffset从0开始到contentSize.width/2的距离内不断循环，这里需要注意contentSize是怎么设置才能达到想要的效果

if (!self.needAnimating) return;

if (self.isAnimating) return;

[self setContentOffset:CGPointZero];

self.isAnimating = YES;

NSTimeInterval animationDuration = (self.contentSize.width/self.scrollSpeed);

[UIView animateWithDuration:animationDuration

delay:0

options:UIViewAnimationOptionCurveLinear

animations:^{

CGPoint finalPoint = CGPointZero;

if (self.scrollDirection == PMScrollDirectionFromRight)

finalPoint = CGPointMake(self.contentSize.width/2, 0);

else if (self.scrollDirection == PMScrollDirectionFromLeft)

finalPoint = CGPointMake(-self.contentSize.width/2, 0);

self.contentOffset = finalPoint;

} completion:^(BOOL finished) {

if (finished) {

self.isAnimating = NO;

BOOL restartAnimation = (self.numberOfLoops == 0 || self.runningLoops <= self.numberOfLoops);

if (self.finishedBlock)

{

self.finishedBlock((self.runningLoops+1),!restartAnimation);

}

if (restartAnimation)

[self beginAnimation];

else

[self endAnimation:NO];

self.runningLoops++;

}

}];

}

-(void)resetAnimation

{

//重置循环，将计数变为0，然后重新开始滚动

self.isAnimating = NO;

self.runningLoops = 0;

[self beginAnimation];

}

- (void) endAnimation:(BOOL) animated {

if (!self.isAnimating) return;

self.isAnimating = NO;

[self setContentOffset:CGPointZero animated:NO];

}

-(void)setText:(NSString *)text

{

//改变文字，这里我偷了个懒，没有重新去修改contentSize和label的frame， 所以运行效果可能有些问题，根据自己想要的效果进行修改吧

for (UIView *view in self.subviews)

{

if ([view isKindOfClass:[UILabel class]])

{

[(UILabel *)view setText:text];

}

}

}

@end

用法实例：

SEScrollLabel *scrollLabel = [[SEScrollLabel alloc] initWithFrame:CGRectMake(0, 0, 80, 30) labels:@[label, sameLabel] direction:PMScrollDirectionFromRight speed:15 loops:3 completition:^(NSUInteger loopsDone, BOOL isFinished) {

NSLog(@"已经运行了%ld次，循环%@结束", (unsigned long)loopsDone, isFinished ? @"已经": @"尚未");

}];

[self.view addSubview:scrollLabel];

[scrollLabel beginAnimation];

附上效果图一枚:

具体源码请访问 http://www.cnblogs.com/sely-ios/p/4552134.html