简单实现，主要是 CATransition的用法

• MarqueeLabel.h实现

#import <UIKit/UIKit.h>
@class MarqueeLabel;
typedef void(^MarqueeLabelClick)(MarqueeLabel *marqueeLabel,NSInteger  index);

@interface MarqueeLabel : UIView

//要显示的字符数组
@property (nonatomic, strong)NSArray<NSString *>  *titlesArray;

//切换速度
@property (nonatomic, assign)CGFloat   speed;

//字体
@property (nonatomic, strong)UIFont    *textFont;

//字体颜色
@property (nonatomic, strong)UIColor   *textColor;

//切换时间间隔
@property (nonatomic, assign)CGFloat   time;

//点击回调
@property (nonatomic, copy)MarqueeLabelClick  marqueeLabelClick;

- (void)end;

@end

• MarqueeLabel.m实现

#import "MarqueeLabel.h"

#define SPEED (0.5)
#define TIME   (3.0)

@interface MarqueeLabel () {
    
    UILabel     *showLabel;
    
    NSTimer     *timer;
    
    NSInteger   count;
}

@end

@implementation MarqueeLabel

- (id)init {
    self = [super init];
    if (self) {
        _textFont = [UIFont systemFontOfSize:14.0];
        _textColor = [UIColor blackColor];
        _time = TIME;
        _speed = SPEED;
        [self subViewInit];
    }
    return self;
}

- (id)initWithFrame:(CGRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
        _textFont = [UIFont systemFontOfSize:14.0];
        _textColor = [UIColor blackColor];
        _time = TIME;
        _speed = SPEED;
        [self subViewInit];
    }
    return self;
}

- (void)layoutSubviews {
    showLabel.frame = CGRectMake(0, 0, self.frame.size.width, self.frame.size.height);
}

- (void)subViewInit {
    self.clipsToBounds = YES;
    showLabel = [[UILabel alloc]init];
    showLabel.textColor = _textColor;
    showLabel.font = _textFont;
    showLabel.clipsToBounds = YES;
    showLabel.userInteractionEnabled = YES;
    [self addSubview:showLabel];
    
    UITapGestureRecognizer  *tap = [[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(labelClick)];
    [showLabel addGestureRecognizer:tap];
}

- (void)setTextFont:(UIFont *)textFont {
    _textFont = textFont;
    showLabel.font = _textFont;
}

- (void)setTextColor:(UIColor *)textColor {
    _textColor = textColor;
    showLabel.textColor = _textColor;
}

- (void)setTitlesArray:(NSArray *)titlesArray {
    _titlesArray = titlesArray;
    if (titlesArray && titlesArray.count > 0) {
        count = 0;
        showLabel.text = [_titlesArray firstObject];
        if (!timer) {
            timer = [NSTimer timerWithTimeInterval:_time target:self selector:@selector(timer) userInfo:nil repeats:YES];
            [[NSRunLoop currentRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];
        }
    } else {
        
        if (timer) {
            [timer invalidate];
            timer = nil;
        }
    }
}

- (void)timer{
    dispatch_async(dispatch_get_main_queue(), ^{
        if (_titlesArray && _titlesArray.count > 0) {
            count ++;
            if (count >= _titlesArray.count ) {
                count = 0;
            }
            NSString  *mes = _titlesArray[count];
            [self animation:mes];
            
        }
    });
}

- (void)animation:(NSString *)mes {
    CATransition *animation = [CATransition animation];
    //设置运动时间
    animation.duration = _speed;

//    kCATransitionFade
//    kCATransitionMoveIn
//    kCATransitionPush
//    kCATransitionReveal
    animation.type = kCATransitionPush;
    
//    kCATransitionFromRight
//    kCATransitionFromLeft
//    kCATransitionFromTop
//    kCATransitionFromBottom
    animation.subtype = kCATransitionFromTop;
    //设置运动速度
    animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
    showLabel.text = mes;
    [showLabel.layer addAnimation:animation forKey:@"animation"];
}

- (void)end {
    if (timer) {
        [timer invalidate];
        timer = nil;
    }
}

- (void)labelClick {
    if (self.marqueeLabelClick) {
        self.marqueeLabelClick(showLabel.text,count);
    }
}

@end

• 使用

    MarqueeLabel *label = [[MarqueeLabel alloc]initWithFrame:CGRectMake(20, 64, self.view.frame.size.width - 40, 30)];
    label.titlesArray = @[@"哈哈哈哈",@"呵呵呵呵呵呵呵呵呵呵"];
    label.backgroundColor = [UIColor lightGrayColor];
    label.marqueeLabelClick = ^(NSString *marqueeString,NSInteger  index){
        NSLog(@"______%@____%ld",marqueeString,index);
    };
    [self.view addSubview:label];