iOS实现一个高性能的跑马灯

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

复制代码

//
//  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)frame
                       config:(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