iOS跑马灯效果

一.简介

跑马灯其实就是一串文字的轮播，实现的方式有很多种。这里我只介绍一种，通过CADisplayLink与UIScrollView来实现轮播。

二.OC版本

.h

/**
 显示的文字
 */
@property (nonatomic , strong )NSString *text;
/**
 字体
 */
@property (nonatomic , strong , readonly)UIFont *font;
/**
 背景
 */
@property (nonatomic , strong)UIColor *bgColor;
/**
 字体颜色
 */
@property (nonatomic , strong)UIColor *textColor;
/**
 每帧移动距离
 */
@property (nonatomic , assign)CGFloat slidingSpeed;
/**
 设置控件值
 @param text 显示文字
 @param font 字体
 */
- (void)ay_setText:(NSString*)text Font:(UIFont *)font;
/**
 开启暂停滚动
 @param paused 滚动状态
 */
- (void)ay_setPaused:(BOOL)paused;

.m
初始化方法

- (instancetype)initWithFrame:(CGRect)frame{
    if (self = [super initWithFrame:frame]) {
        self.showsVerticalScrollIndicator = NO;
        self.showsHorizontalScrollIndicator = NO;
    }
    return self;
}

设置文本内容的方法

- (void)setText:(NSString *)text{
    [self ay_setText:text Font:nil];
}

对整个UIScrollView的布局

- (void)ay_setText:(NSString *)text Font:(UIFont *)font{
// self_w是UIScrollview的真实宽度
    self_w = (UIScreen.mainScreen.bounds.size.width - 24 - 24)/4 - 8;
    _text = text;
    _font = font ? font : kDefaultFont;
    labelSize = [_text boundingRectWithSize:CGSizeMake(CGFLOAT_MAX, 100) options:NSStringDrawingUsesFontLeading attributes:@{NSFontAttributeName:_font} context:nil].size;
    CGSize labelSizeFrame = labelSize;
    labelSizeFrame.width = labelSizeFrame.width + 6;
    labelSize = labelSizeFrame;
    
    CGRect selfFrame = self.frame;
    selfFrame.size.height = _scrollerLabelSize.height > labelSize.height ? _scrollerLabelSize.height : labelSize.height;
    self.frame = selfFrame;
    
    if (!_textLabel) {[self addTxtLabel:text];}

    self.contentSize = CGSizeMake(self_w > labelSize.width? self_w : labelSize.width*2 + self_w, selfFrame.size.height);
    if (!_displayLink) {
        _displayLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(ay_scrollingLabelAction)];
        [_displayLink addToRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
    }
    //自动判断 是否循环播放 当然也可以外部手动控制
    if (self_w >= labelSize.width) {
        _displayLink.paused = true;
    } else {
        _displayLink.paused = false;
    }
}

这里是label的布局和配置

-(void)addTxtLabel:(NSString*)title {
    for (UIView *view in [self subviews]) {
        [view removeFromSuperview];
    }
    for (int i = 0; i<3; i++) {
        UILabel *textLabel = [[UILabel alloc] initWithFrame:CGRectMake(self_w > labelSize.width ? 0 : i == 2 ? (labelSize.width + self_w): (i*labelSize.width + self_w/2), 0, self_w > labelSize.width ? self_w : i == 1 ? self_w/2 :labelSize.width, self.frame.size.height)];
        textLabel.textAlignment = NSTextAlignmentCenter;
        textLabel.font = _font;
        if (i == 1) {
            textLabel.textColor = [UIColor clearColor];
        } else {
            textLabel.textColor = _textColor;
        }
        textLabel.text = _text;
        [self addSubview:textLabel];
    }
    _scrollerLabelSize = self.frame.size;
}

循环方法

- (void)ay_scrollingLabelAction{
    CGPoint point = self.contentOffset;
    if (point.x < labelSize.width + self_w/2) {
        point.x += _slidingSpeed ? _slidingSpeed : 1;
    }else{
        point.x = 1;
    }
    self.contentOffset = point;
}

其他的一些暂定、开始、以及CADisplayLink释放方法

- (void)ay_setPaused:(BOOL)paused{
    _displayLink.paused = paused;
}

- (void)setBgColor:(UIColor *)bgColor{
    _bgColor = bgColor;
    self.backgroundColor = bgColor;
}

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

- (void)dealloc{
    [_displayLink invalidate];
    [_displayLink removeFromRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
}

此方法来自百度搜索，我做了简单的优化解决了轮播卡顿问题，下面我自己手写了swift的初稿 逻辑更完整

三.Swift

直接上代码 可运行，不懂得地方欢迎交流

import Foundation

class ZHJRunningLight: UIScrollView {
    
    var text: String?
    var font: UIFont?
    var bgColor: UIColor?
    var textColor: UIColor?
    var slidingSpeed: CGFloat?
    var displayLink: CADisplayLink?
    var zhjSize: CGSize?
    var labelSize: CGSize?
    var isPaused: Bool = true
    
    init(frame: CGRect,color: UIColor,bgColor: UIColor) {
        super.init(frame: frame)
        zhjSize = frame.size
        self.textColor = color
        self.bgColor = bgColor
        showsVerticalScrollIndicator = false
        showsHorizontalScrollIndicator = false
    }
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        showsVerticalScrollIndicator = false
        showsHorizontalScrollIndicator = false
    }
    /**
     控件布局
     */
    func addTxtLabel() {
        guard let zhjSize = self.zhjSize,let labelSize = self.labelSize else {return}
        removeAllSubViews()
        for i in 0..<3 {
            let x = isPaused ? 0 : i == 2 ? (labelSize.width + zhjSize.width) : CGFloat(CGFloat(i) * labelSize.width + zhjSize.width/2)
            let y = 0
            let w = isPaused ? zhjSize.width : i == 1 ? zhjSize.width/2 : labelSize.width
            let h = zhjSize.height
            
            let label = UILabel(frame: CGRect(x: x, y: CGFloat(y), width: w, height: h))
            label.text = self.text
            label.textAlignment = .center
            if i == 1{
                label.textColor = UIColor.clear
            } else {
                label.textColor = self.textColor
            }
            label.font = self.font
            label.backgroundColor = UIColor.clear
            addSubview(label)
        }
    }
    /**
     设置控件值
     
     @param text 显示文字
     @param font 字体
     */
    func zhj_setTextAndFont(text: String,font: UIFont = UIFont.systemFont(ofSize: 15.0)) {
//        self.slidingSpeed = 1 ?? 1
        self.text = text
        self.font = font
        self.labelSize = text.WithStrigFontSize(font, sizeFont: nil, width: nil)
        
        var labelSizeFrame: CGSize = self.labelSize!
        labelSizeFrame.width = labelSizeFrame.width + 6;
        self.labelSize = labelSizeFrame
        
        guard let zhjSize = self.zhjSize,let labelSize = self.labelSize else {alert("请给控件大小赋值");return}
        
        var selfFrame: CGRect = frame
        selfFrame.size.height = zhjSize.height > labelSize.height ? zhjSize.height : labelSize.height
        self.frame = selfFrame;
        
        (zhjSize.width >= labelSize.width) ? (isPaused = true) : (isPaused = false)
        
        addTxtLabel()
        
        self.contentSize = CGSize(width: isPaused ? zhjSize.width : labelSize.width*2 + zhjSize.width, height: selfFrame.size.height)
        
        if displayLink == nil {
            displayLink = CADisplayLink(target: self, selector: #selector(zhj_scrollingLabelAction))
            displayLink?.add(to: RunLoop.current, forMode: .defaultRunLoopMode)
        }
        
        if (isPaused) {
            displayLink?.isPaused = true
        } else {
            displayLink?.isPaused = false
        }
    }
    
    func zhj_scrollingLabelAction() {
        var point: CGPoint = self.contentOffset
        if (point.x < labelSize!.width + zhjSize!.width/2) {
            point.x += slidingSpeed ?? 1
        }else{
            point.x = 1;
        }
        self.contentOffset = point;
    }
    
    /**
     开启暂停滚动
     
     @param paused 滚动状态
     */
    func zhj_setPaused(ispaus: Bool) {
        displayLink?.isPaused = ispaus
    }
    
    deinit {
        displayLink?.invalidate()
        displayLink?.remove(from: .current, forMode: .defaultRunLoopMode)
    }
}