iOS 绘制虚线的三种方法

方法一：通过Quartz 2D 在 UIView drawRect:方法进行绘制虚线

- (void)drawRect:(CGRect)rect { // 可以通过 setNeedsDisplay 方法调用 drawRect:
    // Drawing code
    CGContextRef context =UIGraphicsGetCurrentContext();
    // 设置线条的样式
    CGContextSetLineCap(context, kCGLineCapRound);
    // 绘制线的宽度
    CGContextSetLineWidth(context, 3.0);
    // 线的颜色
    CGContextSetStrokeColorWithColor(context, [UIColor orangeColor].CGColor);
    // 开始绘制
    CGContextBeginPath(context);
    // 设置虚线绘制起点
    CGContextMoveToPoint(context, 10.0, 20.0);
    // lengths的值｛10,10｝表示先绘制10个点，再跳过10个点，如此反复
    CGFloat lengths[] = {10,10};
    // 虚线的起始点
    CGContextSetLineDash(context, 0, lengths,2);
    // 绘制虚线的终点
    CGContextAddLineToPoint(context, 310.0,20.0);
    // 绘制
    CGContextStrokePath(context);
    // 关闭图像
    CGContextClosePath(context);
}

方法二:通过 Quartz 2D 在 UIImageView 绘制虚线

/** 
* 通过 Quartz 2D 在 UIImageView 绘制虚线
* 
* param imageView 传入要绘制成虚线的imageView 
* return 
*/
- (UIImage *)drawLineOfDashByImageView:(UIImageView *)imageView { 
    // 开始 划线的frame 
    UIGraphicsBeginImageContext(imageView.frame.size); 
    [imageView.image drawInRect:CGRectMake(0, 0, imageView.frame.size.width, imageView.frame.size.height)]; 
    // 获取上下文 
    CGContextRef line = UIGraphicsGetCurrentContext(); 
    // 设置线条终点的形状 
    CGContextSetLineCap(line, kCGLineCapRound); 
    // 设置虚线的长度 和 间距 
    CGFloat lengths[] = {5,5}; 
    CGContextSetStrokeColorWithColor(line, [UIColor greenColor].CGColor); 
    // 开始绘制虚线 
    CGContextSetLineDash(line, 0, lengths, 2); 
    CGContextMoveToPoint(line, 0.0, 2.0); 
    CGContextAddLineToPoint(line, 300, 2.0); 
    CGContextStrokePath(line); 
    // UIGraphicsGetImageFromCurrentImageContext()返回的就是image  
    return UIGraphicsGetImageFromCurrentImageContext(); 
}

方法三：通过CAShapeLayer 方式绘制虚线

/**
 *  通过 CAShapeLayer 方式绘制虚线
 *
 *  param lineView:       需要绘制成虚线的view
 *  param lineLength:     虚线的宽度
 *  param lineSpacing:    虚线的间距
 *  param lineColor:      虚线的颜色
 *  param lineDirection   虚线的方向  YES 为水平方向， NO 为垂直方向
 **/
- (void)drawLineOfDashByCAShapeLayer:(UIView *)lineView lineLength:(int)lineLength lineSpacing:(int)lineSpacing lineColor:(UIColor *)lineColor lineDirection:(BOOL)isHorizonal {

    CAShapeLayer *shapeLayer = [CAShapeLayer layer];

    [shapeLayer setBounds:lineView.bounds];

    if (isHorizonal) {

        [shapeLayer setPosition:CGPointMake(CGRectGetWidth(lineView.frame) / 2, CGRectGetHeight(lineView.frame))];

    } else{
        [shapeLayer setPosition:CGPointMake(CGRectGetWidth(lineView.frame) / 2, CGRectGetHeight(lineView.frame)/2)];
    }

    [shapeLayer setFillColor:[UIColor clearColor].CGColor];
    //  设置虚线颜色为blackColor
    [shapeLayer setStrokeColor:lineColor.CGColor];
    //  设置虚线宽度
    if (isHorizonal) {
        [shapeLayer setLineWidth:CGRectGetHeight(lineView.frame)];
    } else {

        [shapeLayer setLineWidth:CGRectGetWidth(lineView.frame)];
    }
    [shapeLayer setLineJoin:kCALineJoinRound];
    //  设置线宽，线间距
    [shapeLayer setLineDashPattern:[NSArray arrayWithObjects:[NSNumber numberWithInt:lineLength], [NSNumber numberWithInt:lineSpacing], nil]];
    //  设置路径
    CGMutablePathRef path = CGPathCreateMutable();
    CGPathMoveToPoint(path, NULL, 0, 0);

    if (isHorizonal) {
        CGPathAddLineToPoint(path, NULL,CGRectGetWidth(lineView.frame), 0);
    } else {
        CGPathAddLineToPoint(path, NULL, 0, CGRectGetHeight(lineView.frame));
    }

    [shapeLayer setPath:path];
    CGPathRelease(path);
    //  把绘制好的虚线添加上来
    [lineView.layer addSublayer:shapeLayer];
}