iOS 绘制虚线的三种方法

总结了三种绘制虚线的方法：

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 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];
}