Can I disable autolayout for a specific subview at runtime?

I have a view that needs to have its frame manipulated programmatically - it's a kind of document view that wraps to its content which is then scrolled and zoomed around a superview by manipulating the frame origin. Autolayout fights with this at runtime.

Disabling autolayout completely seems a bit harsh because it could reasonably be used to handle layout for the other views. It seems like what I might want is some kind of "null constraint".

Solution 1:

I had the same problem. But I have resolved it.
Yes, you can disable auto layout at runtime for a specific UIView, instead of disabling it for the whole xib or storyboard which is set by default in Xcode 4.3 and later.

Set translatesAutoresizingMaskIntoConstraints to YES, before you set the frame of your subview:

self.exampleView.translatesAutoresizingMaskIntoConstraints = YES;
self.exampleView.frame = CGRectMake(20, 20, 50, 50);

Solution 2:

I had a similar issue where Autolayout was overriding some of my frame-setting at run time (I had a dynamic view that in some cases pushed a new view controller...pushing and then pressing Back would reset the initial view).

I got around this by putting my manipulation code in viewDidLayoutSubviews of my View Controller. This seems to get called after whatever constraint mojo gets called, but before viewDidAppear, so the user is none the wiser.

Solution 3:

Perhaps just setting translatesAutoresizingMaskIntoConstraints to YES (and not adding additional constraints affecting that view) will let you set the frame without fighting the auto layout system.

Solution 4:

In iOS 8 you can set an NSLayoutConstraint to be active or not. So if I'm using interface builder, I add all my constraints to an OutletCollection and then activate or deactivate using:

NSLayoutConstraint.deactivateConstraints(self.landscapeConstraintsPad)
NSLayoutConstraint.activateConstraints(self.portraitConstraintsPad)

The particular application I'm using it for here is having different constraints in portrait and landscape mode and I activate/deactivate based on the rotation of the device. It means I can create some complex layout changes all in interface builder for both orientations, and still use auto layout without the verbose auto layout code.

Or you can activate / deactivate using removeConstraints and addConstraints.

Solution 5:

I don't know if this will help anyone else, but I wrote a category to make this convenient because I find myself doing this a lot.

UIView+DisableAutolayoutTemporarily.h

#import <UIKit/UIKit.h>

@interface UIView (DisableAutolayoutTemporarily)

// the view as a parameter is a convenience so we don't have to always
// guard against strong-reference cycles
- (void)resizeWithBlock:(void (^)(UIView *view))block;

@end

UIView+DisableAutolayoutTemporarily.m

#import "UIView+DisableAutoResizeTemporarily.h"
@implementation UIView (DisableAutoResizeTemporarily)

- (void)resizeWithBlock:(void (^)(UIView * view))block
{
    UIView *superview = self.superview;
    [self removeFromSuperview];
    [self setTranslatesAutoresizingMaskIntoConstraints:YES];
    __weak UIView *weakSelf = self;
    block(weakSelf);
    [superview addSubview:self];
}

@end

I use it like this:

[cell.argumentLabel resizeWithBlock:^(UIView *view) {
    [view setFrame:frame];
}];

Hope it helps.