因项目需求，要做一个文字轮播用来展示一些通知内容，以前也有过这个需求，但之前都是在网上找的第三方，现在有点时间就自己写了个简单的。

整体思路：用一个UILabel来展示内容，通过UIView动画来实现滚动效果，通过控制其坐标和隐藏状态来修改其滚动的起始位置。实现比较简单，活不多说，直接贴代码了。

.h文件

#import <UIKit/UIKit.h>  
  
@protocol YMNoticeScrollViewDelegate  
  
@optional  
/// 点击代理  
- (void)noticeScrollDidClickAtIndex:(NSInteger)index content:(NSString *)content;  
  
@end  
  
@interface YMNoticeScrollView : UIView  
  
@property (nonatomic, weak) id<YMNoticeScrollViewDelegate> delegate;  
  
/// 滚动文字数组  
@property (nonatomic, strong) NSArray *contents;  
  
/// 文字停留时长，默认4S  
@property (nonatomic, assign) NSTimeInterval timeInterval;  
  
/// 文字滚动时长，默认0.3S  
@property (nonatomic, assign) NSTimeInterval scrollTimeInterval;  
@end  

.m文件

#import "YMNoticeScrollView.h"  
  
@implementation YMNoticeScrollView  
{  
    UILabel *_scrollLbl;  
    NSTimer *_timer;  
    NSUInteger _count;  
    CGFloat Width;  
    CGFloat Height;  
}  
- (instancetype)initWithFrame:(CGRect)frame {  
    if (self = [super initWithFrame:frame]) {  
        Width = frame.size.width;  
        Height = frame.size.height;  
        _timeInterval = 4;  
        _scrollTimeInterval = 0.3;  
        [self initSubViews];  
    }  
    return self;  
}  
  
/// 创建Label  
- (void)initSubViews {  
    self.clipsToBounds = YES;  
      
    _scrollLbl = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, Width, Height)];  
    _scrollLbl.textColor = TEXT_COLOR_LEVEL_2;  
    _scrollLbl.font = SystemFont(12);  
    _scrollLbl.numberOfLines = 2;  
    _scrollLbl.userInteractionEnabled = YES;  
    UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(clickAction)];  
    [_scrollLbl addGestureRecognizer:tap];  
    [self addSubview:_scrollLbl];  
}  
// 开启定时器  
- (void)startTimer {  
    if (!_timer) {  
        _timer = [NSTimer timerWithTimeInterval:_timeInterval target:self selector:@selector(timerMethod) userInfo:nil repeats:YES];  
        [[NSRunLoop currentRunLoop] addTimer:_timer forMode:NSRunLoopCommonModes];  
    }  
}  
  
/// 定时器方法  
- (void)timerMethod {  
    _count++;  
    if (_count == _contents.count) {  
        _count = 0;  
    }  
    /// 两次动画实现类似UIScrollView的滚动效果，控制坐标和隐藏状态  
    [UIView animateWithDuration:_scrollTimeInterval animations:^{  
        _scrollLbl.frame = CGRectMake(0, -Height, Width, Height);  
    } completion:^(BOOL finished) {  
        _scrollLbl.hidden = YES;  
        _scrollLbl.frame = CGRectMake(0, Height, Width, Height);  
        _scrollLbl.hidden = NO;  
        [UIView animateWithDuration:_scrollTimeInterval animations:^{  
            _scrollLbl.text = [self getCurrentContent];  
            _scrollLbl.frame = CGRectMake(0, 0, Width, Height);  
        } completion:^(BOOL finished) {  
              
        }];  
    }];  
}  
/// 获取要展示的内容数组  
- (void)setContents:(NSArray *)contents {  
    // 判断是否要重新赋值  
    if ([self array:contents isEqualTo:_contents]) {  
          
        return;  
    }  
    _contents = contents;  
    [self reset];  
    if (!contents || contents.count == 0) {  
        return;  
    }  
    [self startTimer];  
}  
  
/// 重置初始状态  
- (void)reset {  
      
    _count = 0;  
    _scrollLbl.frame = CGRectMake(0, 0, Width, Height);  
    _scrollLbl.text = [self getCurrentContent];  
    [_timer invalidate];  
    _timer = nil;  
}  
/// 获取当前要展示的内容  
- (NSString *)getCurrentContent {  
    if (!_contents || _contents.count == 0) {  
        return nil;  
    }  
    return _contents[_count];  
}  
/// 比较两个数组内容是否相同  
- (BOOL)array:(NSArray *)array1 isEqualTo:(NSArray *)array2 {  
    if (array1.count != array2.count) {  
        return NO;  
    }  
    for (NSString *str in array1) {  
        if (![array2 containsObject:str]) {  
            return NO;  
        }  
    }  
    return YES;  
}  
/// 点击事件  
- (void)clickAction {  
      
    if (_delegate && [(id)_delegate respondsToSelector:@selector(noticeScrollDidClickAtIndex:content:)]) {  
        [_delegate noticeScrollDidClickAtIndex:_count content:_contents[_count]];  
    }  
}  

如果各位大神发现什么问题，还望指正。
转载请注明原文链接：https://www.jianshu.com/p/6e67c879282a