iOS7与Interface Builder生成的NSIBPrototypingLayoutConstraint自动布局约束有关

Question

以前在iOS6中,我的聊天消息视图控制器在IB中通过精心构造的自动布局约束正确显示和动画.这是在Xcode 5中删除约束的当前视图层次结构:

在升级到XCode 5和iOS7之后,我发现我需要清除所有旧约束以便考虑默认的半透明状态栏,否则我的工具栏将属于状态栏.尽管使用UIRectEdgeNone调用setEdgesForExtendedLayout:发生了这种情况.

我现在正试图在viewDidLoad中以编程方式创建所有约束:

// self.view.translatesAutoresizingMaskIntoConstraints = NO; // errors either way
NSArray *viewHorizConstraints = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|[_toolbar]|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(_toolbar)];
[self.view addConstraints:viewHorizConstraints];
viewHorizConstraints = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|[_viewContainer]|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(_viewContainer)];
[self.view addConstraints:viewHorizConstraints];

NSArray *viewVertConstraints = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|-(20)-[_toolbar(44)]-[_viewContainer]|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(_toolbar, _viewContainer)];
[self.view addConstraints:viewVertConstraints];

NSArray *tableContainerVertConstraints = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|[_tableView(<=460@999)][_viewInputContainer(44)]|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(_tableView, _viewInputContainer)];
[_viewTableContainer addConstraints:tableContainerVertConstraints];


NSArray *containerVertConstraints = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|[_viewTableContainer][_viewOptions]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(_viewTableContainer, _viewOptions)];
[_viewContainer addConstraints:containerVertConstraints];

//    _constraintContainerVertSpace = [NSLayoutConstraint constraintWithItem:_viewTableContainer attribute:NSLayoutAttributeTrailing relatedBy:NSLayoutRelationEqual toItem:_viewContainer attribute:NSLayoutAttributeTrailing multiplier:1 constant:0]; // same as below

containerVertConstraints = [NSLayoutConstraint constraintsWithVisualFormat:@"V:[_viewTableContainer]|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(_viewTableContainer)];
_constraintContainerVertSpace = [containerVertConstraints lastObject];
[_viewContainer addConstraint:_constraintContainerVertSpace];

containerVertConstraints = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|-(>=0)-[_viewOptions]-(>=-216@999)-|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(_viewOptions)];
[_viewContainer addConstraints:containerVertConstraints];

但是,如果我尝试更改containerView和tableContainerView之间的垂直空间约束,我会收到错误.(我正在尝试调整tableContainerView的大小以缩小键盘的外观.)

[UIView animateWithDuration:0.25f
                      delay:0
                    options:UIViewAnimationOptionCurveEaseInOut
                 animations:^{
                     _constraintContainerVertSpace.constant = -keyboardHeight;
                 } completion:nil];

这些是无法同时满足的约束:

(
"<NSIBPrototypingLayoutConstraint:0x140d7bb0 'IB auto generated at build time for view with fixed frame' V:|-(460)-[UIView:0x140ddef0]   (Names: '|':UIView:0x140dde60 )>",
"<NSIBPrototypingLayoutConstraint:0x140d7c10 'IB auto generated at build time for view with fixed frame' V:[UIView:0x140ddef0(44)]>",
"<NSLayoutConstraint:0x14d9db30 V:[UIView:0x140ddef0]-(0)-|   (Names: '|':UIView:0x140dde60 )>",
"<NSIBPrototypingLayoutConstraint:0x140e0290 'IB auto generated at build time for view with fixed frame' V:|-(0)-[UIView:0x140dde60]   (Names: '|':UIView:0x140dddd0 )>",
"<NSLayoutConstraint:0x14d9df60 V:[UIView:0x140dde60]-(-216)-|   (Names: '|':UIView:0x140dddd0 )>",
"<NSIBPrototypingLayoutConstraint:0x140e0830 'IB auto generated at build time for view with fixed frame' V:|-(64)-[UIView:0x140dddd0]   (Names: '|':UIView:0x140e0470 )>",
"<NSLayoutConstraint:0x14d9d820 V:[UIView:0x140dddd0]-(0)-|   (Names: '|':UIView:0x140e0470 )>",
"<NSAutoresizingMaskLayoutConstraint:0x1403a0b0 h=--& v=--& V:[UIView:0x140e0470(568)]>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x14d9db30 V:[UIView:0x140ddef0]-(0)-|   (Names: '|':UIView:0x140dde60 )>

UIView:在这种情况下,0x140dde60是_viewTableContainer.0x140ddef0 = _viewInputContainer.0x140dddd0 = _viewContainer.

为什么这个NSIBPrototypingLayoutConstraint V:| - (460) - [UIView:0x140ddef0(_viewInputContainer)]是在我将translateAutoresizingMaskIntoConstraints设置为NO时由IB创建的,当我已经在_viewInputContainer和_tableView之间定义了明确的垂直约束时？

我尝试过在仪器中使用Cocoa Layout,但是有太多的噪音让人感觉不到.

Answer 1

除了使用translatesAutoresizingMaskIntoConstraints之外,我还必须手动删除视图上的约束.

[_viewContainer removeConstraints:_viewContainer.constraints];
[self.view removeConstraints:self.view.constraints];

添加这些更改后,动画没有更多错误.

Answer 2

为了去除NSIBPrototypingLayoutConstraintIB生成的,可以通过在IB上添加一些伪约束来解决它,并设置它们remove at build time.然后,IB不会NSIBPrototypingLayoutConstraint为你生成.