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As far as I know, views displayed by constraints don't got a frame, so what should I do when I want to draw some lines in these views? Methods like moveToPoint do need a CGRect.

Here's my check: NSLog(@"%f,%f,%f,%f",self.contentView.frame.origin.x,self.contentView.frame.origin.y,self.contentView.frame.size.width,self.contentView.frame.size.height); And the result is 0.000000,0.000000,0.000000,0.000000

For more details, here's my code:

-(void)loadView { self.view = [[UIView alloc]init]; self.titleView = [[UIView alloc]init]; self.placesHolder = [[UIView alloc]init]; self.contentView = [[UIView alloc]init]; self.titleView.translatesAutoresizingMaskIntoConstraints = NO; self.placesHolder.translatesAutoresizingMaskIntoConstraints = NO; self.contentView.translatesAutoresizingMaskIntoConstraints = NO; self.titleView.backgroundColor = [UIColor grayColor]; self.placesHolder.backgroundColor = [UIColor blueColor]; self.contentView.backgroundColor = [UIColor redColor]; [self.view addSubview:self.titleView]; [self.view addSubview:self.placesHolder]; [self.view addSubview:self.contentView]; NSDictionary *timeLineViewMap = @{@"titleView":self.titleView, @"placesHolder":self.placesHolder, @"contentView":self.contentView }; NSArray *titleHorizon = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|[titleView]|" options:0 metrics:nil views:timeLineViewMap]; NSArray *placesHolderHorizon = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|[placesHolder(==58)]-0-[contentView]|" options:0 metrics:nil views:timeLineViewMap]; NSArray *titleVertical = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|[titleView(==58)]-0-[placesHolder]|" options:0 metrics:nil views:timeLineViewMap]; NSArray *contentViewConstrain = [NSLayoutConstraint constraintsWithVisualFormat:@"V:[titleView]-0-[contentView]|" options:0 metrics:nil views:timeLineViewMap]; [self.view addConstraints:titleHorizon]; [self.view addConstraints:placesHolderHorizon]; [self.view addConstraints:titleVertical]; [self.view addConstraints:contentViewConstrain]; }
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  • To be honest, I really don't know there is a most useful answer function, thanks for telling. Commented Dec 12, 2014 at 12:45
  • Double-check whether self.contentView is nil at this time. Commented Dec 12, 2014 at 12:57
  • The code you posted is not related to custom view drawing, they are standard UIView instances? And since these views don't have an intrinsic content size they might get set to 0 width/height… especially contentView. Commented Dec 12, 2014 at 13:02
  • that is just a part of my code, in fact I add some custom views to the contentView, but the bounds was still 0. speaking intrinsic content, I didn't really think about that, let me try. Commented Dec 12, 2014 at 13:09

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Of course UIView does have a frame even with AutoLayout. You just don't set the values manually, AutoLayout is doing that for you. Methods like setFrame: are still called. Simply implement drawRect: like you always did.

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But when I print the size of the bounds, it is 0,0,0,0, which means the view didn't set bounds at all, did I miss something?
Then most likely your constraints forced the view to have a size of {0, 0}. Try setting explicit size and width constraints for debugging.
Did you actually look at the rect argument that is passed to drawRect:? Or did you look at self.bounds (which is what you should look at)? Or something else? Because if some object in the call-chain is nil you'll also get the zero-rect.
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Well, problem kind of solved, it seems that a frame of a view don't get a size until it's on the viewDidAppear move. Then I checked some other questions like iOS AutoLayout - get frame size width, which indicate that addConstraints should be put in the viewDidLayoutSubviews method, which is not in the viewController life cycle.

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