iOS实现一个高性能的跑马灯

效果图

该跑马灯完全通过CATextLayer 实现，轻量级，并且通过
系统的位移动画实现滚动效果，避免了使用displaylink造成的性能瓶颈，使用系统动画，系统自动做了很多性能优化，实现更好的性能，并使用遮罩实现展示范围的限定
，实现跑马灯效果

//
//  LBMarqueeLayer.m
//  TEXT
//
//  Created by mac on 2024/4/28.
//  Copyright © 2024 刘博. All rights reserved.
//#import "LBMarqueeLayer.h"@implementation LBMarqueeLayerConfig- (instancetype)init
{self = [super init];if (self) {self.velocity = 20;self.fontSize = 14;self.textColor = [UIColor darkGrayColor];self.pauseDuration = 3;self.blankString = @"  ";}return self;
}@end@interface LBMarqueeLayer () <CAAnimationDelegate>@property (nonatomic, strong) CATextLayer *textLayer;@property (nonatomic, strong) CALayer *maskLayer;@property (nonatomic, strong) LBMarqueeLayerConfig *config;@property (nonatomic, strong) CABasicAnimation *animation;@end@implementation LBMarqueeLayer- (instancetype)initwithFrame:(CGRect)frameconfig:(LBMarqueeLayerConfig *)config
{if ([super init]) {self.frame = frame;self.config = config;[self handleText];[self addSublayer:self.textLayer];}return self;
}- (void)handleText
{CGFloat width = [self.config.text sizeWithAttributes:@{NSFontAttributeName:[UIFont systemFontOfSize:self.config.fontSize]}].width;if (width > CGRectGetWidth(self.bounds)) {NSString *content = [NSString stringWithFormat:@"%@%@%@", self.config.text, self.config.blankString, self.config.text];NSAttributedString *attributedString = [[NSAttributedString alloc] initWithString:content attributes:@{NSFontAttributeName:[UIFont systemFontOfSize:self.config.fontSize]}];self.textLayer.string = attributedString;CGFloat width = [content sizeWithAttributes:@{NSFontAttributeName: [UIFont systemFontOfSize:self.config.fontSize]}].width;self.textLayer.frame = CGRectMake(0, 0, width, CGRectGetHeight(self.bounds));CGFloat toValue = [[NSString stringWithFormat:@"%@%@", self.config.text, self.config.blankString] sizeWithAttributes:@{NSFontAttributeName:[UIFont systemFontOfSize:self.config.fontSize]}].width;self.animation.fromValue = @(0);self.animation.toValue = @(-toValue);self.animation.duration = toValue/self.config.velocity;[self.textLayer addAnimation:self.animation forKey:@"animation"];self.masksToBounds = YES;} else {self.textLayer.string = self.config.text;}}#pragma mark - animationDelegate- (void)animationDidStop:(CAAnimation *)anim finished:(BOOL)flag{if (flag) {dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(self.config.pauseDuration * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{[self.textLayer addAnimation:self.animation forKey:@"animation"];});}}#pragma mark - lazy load- (CATextLayer *)textLayer{if (!_textLayer) {_textLayer = [[CATextLayer alloc] init];_textLayer.frame = CGRectMake(0, 0, CGRectGetWidth(self.frame), CGRectGetHeight(self.frame));_textLayer.alignmentMode = kCAAlignmentLeft;_textLayer.fontSize = 14;_textLayer.foregroundColor = self.config.textColor.CGColor;}return _textLayer;}- (CALayer *)maskLayer{if (!_maskLayer) {_maskLayer = [[CALayer alloc] init];_maskLayer.frame = self.bounds;}return _maskLayer;}- (CABasicAnimation *)animation{if (!_animation) {_animation = [CABasicAnimation animationWithKeyPath:@"transform.translation.x"];if (!self.config.hasPause) {_animation.repeatCount = NSIntegerMax;}_animation.delegate = self;}return _animation;}@end

调用

- (LBMarqueeLayer *)textLayer
{if (!_textLayer) {LBMarqueeLayerConfig *config = [[LBMarqueeLayerConfig alloc] init];config.hasPause = YES;config.pauseDuration = 3;config.blankString = @"      ";config.text = @"这是一首非常好听的歌曲哈哈哈哈";_textLayer = [[LBMarqueeLayer alloc] initwithFrame:CGRectMake(100, 100, 200, 50) config:config];_textLayer.backgroundColor = [UIColor cyanColor].CGColor;}return _textLayer;
}