CODEWITHSUNDEEP
iosobjective-cxcodeswift
jskidd3
jskidd3

Reputation: 4783

Copying frame/bounds/constraints from one view to another

self.blurView = UIVisualEffectView(effect: UIBlurEffect(style: .ExtraLight)) as UIVisualEffectView
self.blurView.frame = self.filterPanel.frame
self.blurView.bounds = self.filterPanel.bounds
self.blurView.addConstraints(self.filterPanel.constraints())
self.view.insertSubview(self.blurView, belowSubview: self.filterPanel)

When attempting to run the code above in viewDidLoad it returns the error below. Why is this? I am simply trying to create a blur view with the same dimensions as the filterPanel view.

2015-02-15 14:44:37.929 App[568:182030] The view hierarchy is not prepared for the constraint: <NSLayoutConstraint:0x18eeac70 H:|-(0)-[UIView:0x1bbe0a70]   (Names: '|':UIView:0x1bbe0a00 )>
    When added to a view, the constraint's items must be descendants of that view (or the view itself). This will crash if the constraint needs to be resolved before the view hierarchy is assembled. Break on -[UIView _viewHierarchyUnpreparedForConstraint:] to debug.
2015-02-15 14:44:37.944 App[568:182030] *** Assertion failure in -[UIVisualEffectView _layoutEngine_didAddLayoutConstraint:roundingAdjustment:mutuallyExclusiveConstraints:], /SourceCache/UIKit/UIKit-3318.16.25/NSLayoutConstraint_UIKitAdditions.m:560
2015-02-15 14:44:37.945 App[568:182030] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Impossible to set up layout with view hierarchy unprepared for constraint.'
*** First throw call stack:
(0x229ba49f 0x30174c8b 0x229ba375 0x2368bd1f 0x264a4295 0x25f63cd3 0x25f63b3f 0x25f63ab3 0x264a43d1 0x25f6c909 0x25f6c87d 0xffe30 0x1019dc 0x25e7b52f 0x25f25385 0x25f252ad 0x25f24843 0x25f24573 0x25f242dd 0x25f24271 0x25e78a6f 0x258a0a0d 0x2589c3e5 0x2589c26d 0x2589bc51 0x2589ba55 0x260dc885 0x260dd62d 0x260e7a39 0x260dba47 0x2914b0d1 0x22980d7d 0x22980041 0x2297e7c3 0x228cc3c1 0x228cc1d3 0x25edf9cf 0x25eda7b1 0xbd574 0xbd690 0x306f4aaf)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb)

Thanks in advance.

Upvotes: 1

Views: 2008

Answers (1)

Ken Thomases
Ken Thomases

Reputation: 90601

The constraints self.filterPanel.constraints() all presumably relate to self.filterPanel and its subviews. Setting those constraints on self.blurView doesn't magically change them to refer to self.blurView and its subviews. You're adding constraints to a view that has nothing to do with it or its subviews.

You would need to go through all of the constraints and build new constraints that are parallel in form but refer to the corresponding view within the self.blurView sub-hierarchy, which is not going to be easy. For one thing, you've just created self.blurView so it presumably has no subviews, yet.

You might try encoding the original view to an archive and then decoding that archive to produce a duplicate sub-hierarchy.

Upvotes: 1

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