在视图中绘制线：不绘制
我正在尝试画一条线，
我的代码是这样的
-(void) drawRect:(CGRect) rect
{
NSLog(@"Reached Draw ARect Function");
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(ctx, 2.0);
CGContextSetRGBStrokeColor(ctx, 1.0, 2.0, 0, 1);
CGContextMoveToPoint(ctx, 0, 0);
CGContextAddLineToPoint( ctx, 100,100);
CGContextStrokePath(ctx);
}
，我从 viewDidLoad 调用如下，
- (void)viewDidLoad {
[super viewDidLoad];
CGRect k = CGRectMake(1.0, 1.0, 100.0, 200.0);
[self.view drawRect:k];
}
有人可以帮助我吗？
I am trying to draw a line
my Code is this
-(void) drawRect:(CGRect) rect
{
NSLog(@"Reached Draw ARect Function");
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(ctx, 2.0);
CGContextSetRGBStrokeColor(ctx, 1.0, 2.0, 0, 1);
CGContextMoveToPoint(ctx, 0, 0);
CGContextAddLineToPoint( ctx, 100,100);
CGContextStrokePath(ctx);
}
and i am calling from the viewDidLoad as follows
- (void)viewDidLoad {
[super viewDidLoad];
CGRect k = CGRectMake(1.0, 1.0, 100.0, 200.0);
[self.view drawRect:k];
}
Can any one help me please?
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评论（3）
您应该子类化
UIView并将线条绘制代码移动到drawRect:方法，就像您正在做的那样（只是希望它是针对 UIView 子类而不是 UIViewController）您必须还要确保您在 InterfaceBuilder 中使用 UIView 子类作为您将绘制到的视图。您不必自己调用此方法。如果您想要为某些内容设置动画，您应该调用
[view setNeedsDisplay];来请求重绘视图。...并且...您应该在调用
CGContextMoveToPoint之前添加CGContextBeginPath(ctx);You should subclass a
UIViewand move your line drawing code to thedrawRect:method, like you are doing (just hoping it's for a UIView subclass and not the UIViewController)You must also make sure you use the UIView subclass in InterfaceBuilder for the view you will be drawing into. You should not have to call this method yourself. If you want to animate something you should call the
[view setNeedsDisplay];to request a redraw of the view....and...you should add
CGContextBeginPath(ctx);just before you callCGContextMoveToPoint您不能直接调用drawRect。
相反，您可以在 UIView 上调用 setNeedsDisplay，返回并等待操作系统稍后使用适当的上下文调用 UIView 的 drawRect。
You can't call drawRect directly.
Instead you call setNeedsDisplay on your UIView, return, and wait for the OS to call the UIView's drawRect with a proper context at some later time.
如果需要
在用户拖动特定视图时动态调用方法，只需放置以下代码：
然后
方法将自动被调用
If there is a need to call
method dynamically while user is dragging a particular view, just place the following code:
then
method will automatically be called