CODEWITHSUNDEEP
iosobjective-cuiviewconstraints
user3214941
user3214941

Reputation: 397

How to change frame of uiview is using autolayout in iOS?

I added 1 view in XIB, it is set autolayout. But when run, i want to to change frame of that view. I know if using autolayout, need to set translatesAutoresizingMaskIntoConstraints = YES in my code. I have done that, I create new frame for that view but it shows the warning message in console:

    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) 
(
    "<NSIBPrototypingLayoutConstraint:0x16e4b750 'IB auto generated at build time for view with fixed frame' V:|-(0)-[UIView:0x16ed3c30]   (Names: '|':UIView:0x16ee06b0 )>",
    "<NSAutoresizingMaskLayoutConstraint:0x16e19e30 h=-&- v=-&- UIView:0x16ed3c30.midY == UIView:0x16ee06b0.midY + 44>",
    "<NSAutoresizingMaskLayoutConstraint:0x16e19e60 h=-&- v=-&- UIView:0x16ed3c30.height == UIView:0x16ee06b0.height>"
)

Will attempt to recover by breaking constraint 
<NSIBPrototypingLayoutConstraint:0x16e4b750 'IB auto generated at build time for view with fixed frame' V:|-(0)-[UIView:0x16ed3c30]   (Names: '|':UIView:0x16ee06b0 )>

Break on objc_exception_throw to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.

This is the code for create new frame, i just want the origin of Y is equal to 0.

self.leftView.frame= CGRectMake(0, 0, 40, self.view.frame.size.height);

How can i fix that bug? Please give some advice. Thanks much.

Upvotes: 0

Views: 2853

Answers (1)

Zhang
Zhang

Reputation: 11607

If I understand you correctly, I think you need to use a stored NSLayoutConstraint variable in your class, then update the constraint's constant value to 0 to make your UIView slide to the top.

Also, when you're using autolayout, you usually set:

myView.translateAutoResizingMaskIntoConstraint = NO;

That's NO instead of YES.

So an example would be something like:

@interface MyViewController()
{
    NSLayoutConstraint *myViewTopConstraint;
}

@end

@implementation MyViewController

-(void)setupMyConstraintsMethod
{
    ...

    // ---------------------------------------------------------------
    // This constraint here says "myView" top edge should be pinned
    // to the top edge of the view controller's view but with an offset
    // of 50 pixels. 
    // ---------------------------------------------------------------
    NSLayoutConstraint *myViewTopConstraint = [NSLayoutConstraint constraintWithItem:self.myView attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeTop multiplier:1.0 constant:50.0];

    [self.view addConstraint:myViewTopConstraint];
}

-(void)buttonPressed:(id)sender
{
    // ------------------------------------------------------------
    // now you want myView's top edge to be at the top of your
    // view controller's view, so you set the constant to 0
    // ------------------------------------------------------------
    myViewTopConstraint.constant = 0;

    // animates the sliding up of "myView"
    [UIView animateWithDuration:0.5 animations:^{
        [self.view layoutIfNeeded];
    }];
}

@end

Upvotes: 1

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