实现上下切换文字效果

哈哈，自己拍的视频制作的gif图，有点low!
效果图

文字滚动.gif

实现思路：首先是要有一个UILabel，数组，定时器。然后在定时器变化的方法里面改变数组的索引，添加动画效果，给UILabel赋值。

HYScrollMessageView.h文件
#import <UIKit/UIKit.h>

@interface HYScrollMessageView : UIView

@property (nonatomic,strong) NSArray *rssArray;
@property (nonatomic,copy) void (^messageClickBlock)();

- (void)makeMsgArr:(NSArray *)rssArray;
- (void)startTimer;
- (void)stopTimer;
@end

HYScrollMessageView.m文件
#import "HYScrollMessageView.h"

@interface HYScrollMessageView()

@property (nonatomic,strong) UILabel *messageLabel;
@property (nonatomic,strong) UIButton *messageBtn;
@property (nonatomic, strong) NSTimer *animationTimer;

@end

static int countInt=0;
@implementation HYScrollMessageView

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        _messageLabel = [[UILabel     alloc]initWithFrame:CGRectMake(0, 0, frame.size.width, frame.size.height)
    ];
        _messageLabel.textColor = [UIColor blackColor];
        _messageLabel.backgroundColor = [UIColor clearColor];
        _messageLabel.font = [UIFont systemFontOfSize:14];
        _messageLabel.lineBreakMode = NSLineBreakByTruncatingTail;
        _messageLabel.numberOfLines = 1;
        [self addSubview:_messageLabel];
    
        _messageBtn = [[UIButton alloc]initWithFrame:CGRectMake(0, 0, frame.size.width, frame.size.height)];
        [_messageBtn addTarget:self action:@selector(messageBtnClicked:) forControlEvents:UIControlEventTouchUpInside];
        [self addSubview:_messageBtn];
    }
    return self;
}

  //按钮点击回调
- (void)messageBtnClicked:(UIButton *)sender
{
    if (self.messageClickBlock) {
        self.messageClickBlock();
    }
}

- (void)makeMsgArr:(NSArray *)rssArray
{
    if (rssArray.count == 0 || rssArray == nil || rssArray == NULL) {
        return;
    }

    self.rssArray = rssArray;
    [self.messageLabel setText:[self.rssArray objectAtIndex:countInt] ];
    //设置定时器
    [self startTimer];
}

//信息的轮播
-(void)displayNews
{
    //增加数组索引
    countInt ++;
    if (countInt >= [_rssArray count]) {
        countInt = 0;
    }
    //实现动画效果
    CATransition *animation = [CATransition animation];
    animation.delegate = self;
    animation.duration = 1;
    animation.timingFunction = UIViewAnimationCurveEaseInOut;
    animation.subtype = kCATransitionFromTop;
    animation.fillMode = kCAFillModeBackwards;
    animation.removedOnCompletion = YES;
    animation.type = @"push";

    [self.messageLabel setText:[self.rssArray objectAtIndex:countInt] ];
    [self.messageLabel.layer addAnimation:animation forKey:@"animationID"];
}

//启用定时器
- (void)startTimer
{
    if (!_animationTimer) {
        self.animationTimer = [NSTimer scheduledTimerWithTimeInterval:2
                                target:self
                              selector:@selector(displayNews)
                              userInfo:nil
                               repeats:YES];
        [[NSRunLoop currentRunLoop] addTimer:self.animationTimer forMode:NSRunLoopCommonModes];
    }
}
  //关闭定时器
- (void)stopTimer
{
    if ([self.animationTimer isValid] == YES)
        [self.animationTimer invalidate];
        self.animationTimer = nil;
    NSLog(@"系统消息定时器停止");
}

@end

使用时操作
#import "ViewController.h"
#import "HYScrollMessageView.h"
#import "WebViewController.h"

@interface ViewController ()

{
    NSArray *msgArray;
}
@property (strong, nonatomic) HYScrollMessageView     *messageView;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    self.title = @"Message";
    msgArray= [NSArray arrayWithObjects:@"今天天气不错,哈哈",@"明天有雨，哈哈",@"后天晴天转多云",@"前天多云转晴，嘿嘿", nil];
    _messageView = [[HYScrollMessageView alloc]initWithFrame:CGRectMake(50, 100, 200, 25)];
    [_messageView makeMsgArr:msgArray];
    __weak typeof (self) myself = self;
    _messageView.messageClickBlock = ^(){
        WebViewController *vc = [[WebViewController alloc] init];
        [myself.navigationController pushViewController:vc animated:YES];
    };
    [self.view addSubview:_messageView];

}

- (void)viewWillAppear:(BOOL)animated
{
     [_messageView startTimer];
}

- (void)viewWillDisappear:(BOOL)animated{
    [_messageView stopTimer];
}

demo地址：https://github.com/huanghaiyan/HYScrollMessage-master