autolayout - figuring out which constraints supersede which - ios

Question

I'm messing around with a really simple app to learn how to use AVFoundation (only been coding at all for about 14 weeks).
Included is a screenshot to help visualize my problem - my vertical constraints work just fine, and my horizontal constraints appear for two buttons that I have. However, my horizontal constraints (which I'm using to center a few objects) do not seem to work for the two labels I have underneath each button.
I wonder if the problem is that some constraints (perhaps the way I've created them) take priority over others and prevent some constraints from appearing properly? Really not sure here.
-(void)setConstraints {
[self.view removeConstraints:self.view.constraints];
UIButton *cameraButton = self.cameraButton;
UILabel *camera = self.videoLabel;
UIButton *libraryButton = self.libraryButton;
UILabel *library = self.libraryLabel;
NSDictionary *views = NSDictionaryOfVariableBindings(camera, cameraButton, libraryButton, library);
//set up top button to be horizontally centered
NSArray *constraints = [NSLayoutConstraint constraintsWithVisualFormat:#"|-[cameraButton]-|"
options:0
metrics:nil
views:views];
//set up top button vertical from top of superview
constraints = [constraints arrayByAddingObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat: #"V:|-175-[cameraButton]"
options:0
metrics:nil
views:views]];
//set up top button label to be horizontally centered
constraints = [constraints arrayByAddingObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat: #"|-[camera]-|"
options:0
metrics:nil
views:views]];
//set up second button to be horizontally centered
constraints = [constraints arrayByAddingObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat: #"|-[libraryButton]-|"
options:0
metrics:nil
views:views]];
//set up label for second button to be horizontally centered
constraints = [constraints arrayByAddingObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat: #"|-[library]-|"
options:0
metrics:nil
views:views]];
//set up vertical constraints by spacing ALL objects appropriately
constraints = [constraints arrayByAddingObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat: #"V:[cameraButton]-[camera]-150-[libraryButton]-[library]"
options:0
metrics:nil
views:views]];
[self.view addConstraints:constraints];
}

Answer 1

My guess is you wanted these views to appear centered. But that isn't what a "|-[view]-|" constraint will do. What you just told the view is, "I want you to fill the entire width of your superview, modulo the default padding". If you were to set a background color on your labels you'd see them extending the entire width of the view.
The easiest solution for you here is to set the text layout to center.