iOS实现一个高性能的跑马灯

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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];}return self;
}@end@interface LBMarqueeLayer ()@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.text];self.textLayer.string = content;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] sizeWithAttributes:@{NSFontAttributeName:[UIFont systemFontOfSize:self.config.fontSize]}].width;self.animation.fromValue = @(0);self.animation.toValue = @(-toValue + 3);self.animation.duration = toValue/self.config.velocity;[self.textLayer addAnimation:self.animation forKey:@"animation"];self.masksToBounds = YES;// self.mask = self.maskLayer;} else {self.textLayer.string = self.config.text;}
}#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"];_animation.repeatCount = NSIntegerMax;}return _animation;
}@end

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