How to constrain a view to the bottom left of a UINavigationBar?

Question

My goal is to add a logo to the bottom left corner of a UINavigationBar, and to add constraints so that it stays there upon rotation.

Here's what I've tried:

UIView* navBarView = [[self navigationController] navigationBar];
UIImageView* logoImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"asdf"]];

[navBarView addSubview:logoImageView];

NSLayoutConstraint *logoConstraintLeftAlign =
    [NSLayoutConstraint constraintWithItem:logoImageView
                                 attribute:NSLayoutAttributeLeft
                                 relatedBy:NSLayoutRelationEqual
                                    toItem:navBarView
                                 attribute:NSLayoutAttributeLeft
                                multiplier:1.0f
                                  constant:0.0f];

NSLayoutConstraint *logoConstraintBottomAlign =
    [NSLayoutConstraint constraintWithItem:logoImageView
                                 attribute:NSLayoutAttributeBottom
                                 relatedBy:NSLayoutRelationEqual
                                    toItem:navBarView
                                 attribute:NSLayoutAttributeBottom
                                multiplier:1.0f
                                  constant:0.0f];

[navBarView addConstraint:logoConstraintLeftAlign];
[navBarView addConstraint:logoConstraintBottomAlign];

But that produces errors regarding some conflicting constraints:

2013-10-17 13:34:07.202 WTTest6[6551:a0b] Unable to simultaneously satisfy constraints.
Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints) 

(
"<NSLayoutConstraint:0x13196350 UIImageView:0x13198280.bottom == UINavigationBar:0x9d98970.bottom>",
"<NSAutoresizingMaskLayoutConstraint:0x1318a6c0 h=--& v=--& UIImageView:0x13198280.midY == + 12>",
"<NSAutoresizingMaskLayoutConstraint:0x1318a6f0 h=--& v=--& V:[UIImageView:0x13198280(24)]>",
"<NSAutoresizingMaskLayoutConstraint:0x131aa0e0 h=-&- v=--& V:[UINavigationBar:0x9d98970(44)]>"

Will attempt to recover by breaking constraint <NSLayoutConstraint:0x13196350 UIImageView:0x13198280.bottom == UINavigationBar:0x9d98970.bottom>

I looked at the refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints, but was a bit overwhelmed by it, as I am just working with constraints for the first time.

I tried setting the frame of the logoImageView, which worked for the default orientation. I suppose I'd have to change the frame each time the orientation changes. But that seems contrary to the point of using AutoLayout and constraints.

So my question is, Can I use constraints to anchor the view like I want, and if so, how do I avoid the NSAutoresizingMaskLayoutConstraint "problem"?

Note that I looked at Putting a custom UIView at the bottom of a UINavigationBar but that suggested using the titleView of the UINavigationBarItem, which is centered, and thus does not help with the left alignment.

Answer 1

Well first off, what I found is that basically ANY time I add a constraint to something and I get conflicts, it's because I did NOT add this to the object I am adding the constraint to:

[someUIView setTranslatesAutoresizingMaskIntoConstraints:NO];

DO NOT put this on the container view, just the subViews.

Answer 2

Set 'autoresizingMask' on 'navigationBar' subviews for your layout. keep setTranslatesAutoresizingMaskIntoConstraints = YES on all subviews.

It works for me.