你可以换成CAshapleLayer;下面的是iphone6模拟器放大到100效果的图片代码

UIBezierPath *circlePath = [UIBezierPath bezierPathWithOvalInRect:rect]; NSArray *xs = @[@(10),@(35),@(60),@(150),@(80)]; NSArray *ys = @[@(100),@(35),@(40),@(200),@(300)]; CGPoint previousCenter = CGPointZero; for (NSUInteger i = 0; i < [xs count]; i++) { CGPoint start = previousCenter; CGPoint end = CGPointMake([xs[i]floatValue], [ys[i]floatValue]); if (i == 0) { [circlePath moveToPoint:start]; } [circlePath addLineToPoint:end]; previousCenter = end; } CAShapeLayer *layer = [CAShapeLayer layer]; layer.path = circlePath.CGPath; layer.strokeColor = [UIColor redColor].CGColor; layer.lineWidth = 10; layer.lineJoin = @"round"; [self.layer addSublayer:layer];

layer.contentsScale = [UIScreen mainScreen].scale;

在你的DrawLayer上设置上面的值。

/* Defines the scale factor applied to the contents of the layer. If * the physical size of the contents is '(w, h)' then the logical size * (i.e. for contentsGravity calculations) is defined as '(w / * contentsScale, h / contentsScale)'. Applies to both images provided * explicitly and content provided via -drawInContext: (i.e. if * contentsScale is two -drawInContext: will draw into a buffer twice * as large as the layer bounds). Defaults to one. Animatable. */ @property CGFloat contentsScale __OSX_AVAILABLE_STARTING (__MAC_10_7, __IPHONE_4_0);

这个属性的默认值是1.

参考代码：

sublayer

DrawLayer *layer = [DrawLayer layer]; layer.contentsScale = [UIScreen mainScreen].scale; layer.frame = layerView.bounds; [layer setNeedsDisplay]; [layerView.layer addSublayer:layer];

layer

@implementation TestView + (Class)layerClass { return [DrawLayer class]; } @end

TestView *layerView = [[TestView alloc] initWithFrame:CGRectMake(0, 0, 500, 300)]; layerView.layer.contentsScale = [UIScreen mainScreen].scale; [layerView.layer setNeedsDisplay]; [self.view addSubview:layerView];