整体实现思路如下图所示：
当需要显示的内容不足以一屏宽度展示时，这个时候创建两个相同内的label,添加到一个containerView中然后对它的layer层作位移动画移动距离为stringRect.width+spacing，动画如此往复即可实现跑马灯效果
image
代码实现如下：
//
// XLScrollLabelView.h
// 跑马灯Demo
//
// Created by xiaoliuTX on 2017/4/24.
// Copyright © 2017年 xiaoliuTX. All rights reserved.
//
#import <UIKit/UIKit.h>
@interface XLScrollLabelView : UIView
@property (nonatomic, strong) NSString *contentTitle;
@property (nonatomic, strong) UIColor *fontColor;
@property (nonatomic, strong) UIColor *backGroundColor;
@property (nonatomic, strong) UIFont *titleFont;
@property (nonatomic, assign) NSInteger padding; //与屏幕左右边缘的距离
@property (nonatomic, assign) NSInteger spacing;
//相邻滚动label间的距离
@property (nonatomic, assign) NSInteger duration;
// 开始动画
- (void)startScrolling;
// 暂停动画
- (void)pauseScrolling;
// 继续动画
- (void)consumeScrolling;
@end
#import "XLScrollLabelView.h"
#define SCreenWidth [UIScreen mainScreen].bounds.size.width
typedef NS_ENUM(NSInteger, ScrollingState) {
ScrollingStateNotBegin = 0,
ScrollingStateScrolling = 1,
ScrollingStateStoped = 2
};
@interface XLScrollLabelView() <CAAnimationDelegate>
@property (nonatomic, strong) UIView *containerView;
@property (nonatomic, strong) UILabel *leftLabel;
@property (nonatomic, strong) UILabel *rightLabel;
@property (nonatomic, assign) CGSize stringRect;
@property (nonatomic, assign) ScrollingState scrollStatus;
@end
@implementation XLScrollLabelView
- (instancetype)initWithFrame:(CGRect)frame {
if (self = [super initWithFrame:frame]) {
//
[self setDefaultUI];
}
return self;
}
- (void)setContentTitle:(NSString *)contentTitle {
_contentTitle = contentTitle;
// duration时间大小为5 lenth/s
self.duration = contentTitle.length / 5;
NSDictionary *attribute = @{NSFontAttributeName:[UIFont systemFontOfSize:14]};
CGSize size = CGSizeMake(2000, CGRectGetHeight(self.bounds));
self.stringRect = [self.contentTitle boundingRectWithSize:size
options:\
NSStringDrawingTruncatesLastVisibleLine |
NSStringDrawingUsesLineFragmentOrigin |
NSStringDrawingUsesFontLeading
attributes:attribute
context:nil].size;
if (self.stringRect.width < SCreenWidth - self.padding) {
self.leftLabel.font = [UIFont systemFontOfSize:14];
CGRect bounds = self.leftLabel.bounds;
bounds.size = self.stringRect;
self.leftLabel.bounds = bounds;
self.leftLabel.center = CGPointMake(SCreenWidth/2, CGRectGetMidY(self.frame));
self.leftLabel.text = self.contentTitle;
self.leftLabel.backgroundColor = [UIColor clearColor];
self.leftLabel.textColor = [UIColor redColor];
self.leftLabel.contentMode = UIViewContentModeLeft;
[self addSubview:self.leftLabel];
} else {
self.containerView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, CGRectGetWidth(self.frame), CGRectGetHeight(self.frame))];
[self addSubview:self.containerView];
self.leftLabel.font = [UIFont systemFontOfSize:14];
self.leftLabel.backgroundColor = self.backgroundColor;
self.leftLabel.textColor = self.fontColor;
self.leftLabel.contentMode = UIViewContentModeLeft;
self.leftLabel.text = self.contentTitle;
self.leftLabel.frame = CGRectMake(self.padding, 0, self.stringRect.width, CGRectGetHeight(self.containerView.frame));
[self.containerView addSubview:self.leftLabel];
self.rightLabel.font = [UIFont systemFontOfSize:14];
self.rightLabel.backgroundColor = self.backgroundColor;
self.rightLabel.textColor = self.fontColor;
self.rightLabel.contentMode = UIViewContentModeLeft;
self.rightLabel.text = self.contentTitle;
self.rightLabel.frame = CGRectMake(CGRectGetMaxX(self.leftLabel.frame)+self.spacing, 0, self.stringRect.width, CGRectGetHeight(self.containerView.frame));
[self.containerView addSubview:self.rightLabel];
}
}
- (void)startScrolling {
CABasicAnimation *scrollAnimation = [CABasicAnimation animationWithKeyPath:@"position"];
scrollAnimation.delegate = self;
scrollAnimation.duration = self.duration;
scrollAnimation.fromValue = [NSValue valueWithCGPoint:self.containerView.layer.position];
scrollAnimation.toValue = [NSValue valueWithCGPoint:CGPointMake(self.containerView.layer.position.x - (self.stringRect.width+self.spacing), self.containerView.layer.position.y)];
// 设置滚动次数无穷大
scrollAnimation.repeatCount = HUGE_VALF;
scrollAnimation.autoreverses = NO;
scrollAnimation.fillMode = kCAFillModeForwards;
scrollAnimation.removedOnCompletion = NO;
[self.containerView.layer addAnimation:scrollAnimation forKey:@"xiaoliuTX"];
self.scrollStatus = ScrollingStateScrolling;
}
- (void)pauseScrolling {
// 暂停动画
if (self.scrollStatus == ScrollingStateScrolling) {
CFTimeInterval pausedTime = [self.containerView.layer convertTime:CACurrentMediaTime() fromLayer:nil];
self.containerView.layer.speed = 0.0;
self.containerView.layer.timeOffset = pausedTime;
self.scrollStatus = ScrollingStateStoped;
}
}
- (void)consumeScrolling {
if (self.scrollStatus == ScrollingStateStoped) {
CFTimeInterval pausedTime = [self.containerView.layer timeOffset];
self.containerView.layer.speed = 1.0;
self.containerView.layer.timeOffset = 0.0;
self.containerView.layer.beginTime = 0.0;
CFTimeInterval timeSincePause = [self.containerView.layer convertTime:CACurrentMediaTime() fromLayer:nil] - pausedTime;
self.containerView.layer.beginTime = timeSincePause;
self.scrollStatus = ScrollingStateScrolling;
}
}
- (void)animationDidStop:(CAAnimation *)anim finished:(BOOL)flag {
NSLog(@"%@ stop is %d",anim,flag);
self.scrollStatus = ScrollingStateStoped;
[self.containerView.layer removeAnimationForKey:@"xiaoliuTX"];
}
- (void)ScrollDidEnd {
}
- (void)setDefaultUI {
self.fontColor = [UIColor blackColor];
self.backgroundColor = [UIColor clearColor];
self.titleFont = [UIFont systemFontOfSize:14];
self.padding = 20;
self.spacing = 40;
}
- (void)setFontColor:(UIColor *)fontColor {
_fontColor = fontColor;
self.leftLabel.textColor = _fontColor;
self.rightLabel.textColor = _fontColor;
}
-(UILabel *)leftLabel {
if (!_leftLabel) {
_leftLabel = [UILabel new];
_leftLabel.font = _titleFont;
}
return _leftLabel;
}
-(UILabel *)rightLabel {
if (!_rightLabel) {
_rightLabel = [UILabel new];
_rightLabel.font = _titleFont;
}
return _rightLabel;
}
@end
效果如下：
image
