iOS约束未按预期更新

Question

我已经添加了约束到3标签关于holderview和也添加了约束holderview关于Superview

NSDictionary *viewsDictionary = NSDictionaryOfVariableBindings(titleLabel);
NSArray *constraints = [NSLayoutConstraint constraintsWithVisualFormat:@"|-[titleLabel]-|"
                                        options:0
                                        metrics:nil
                                          views:viewsDictionary];

[holderView addConstraints:constraints];


viewsDictionary = NSDictionaryOfVariableBindings(setLabel);
constraints = [NSLayoutConstraint constraintsWithVisualFormat:@"|-[setLabel]-|"
                                        options: 0
                                        metrics:nil
                                          views:viewsDictionary];

[holderView addConstraints:constraints];


viewsDictionary = NSDictionaryOfVariableBindings(repLabel);
constraints = [NSLayoutConstraint constraintsWithVisualFormat:@"|-[repLabel]-|"
                                        options:0
                                        metrics:nil
                                          views:viewsDictionary];

[holderView addConstraints:constraints];

viewsDictionary = NSDictionaryOfVariableBindings(titleLabel, setLabel, repLabel);
constraints = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|-[titleLabel]-0-[setLabel]-0-[repLabel]-|"
                                        options:0
                                        metrics:nil
                                          views:viewsDictionary];

[holderView addConstraints:constraints];


NSDictionary *viewsDictionary = NSDictionaryOfVariableBindings(_labelView);
    NSArray *constraints =[NSLayoutConstraint constraintsWithVisualFormat:@"|-[_labelView]-|"
                                                                  options:0
                                                                  metrics:nil
                                                                    views:viewsDictionary];
    [self addConstraints:constraints];

应用程序中有一个缩小圆圈的功能。我希望holderview及其子视图动态收缩。添加约束对holderview有效，但子视图未对齐。

为了缩小，我会随着超级视图帧的变化更新Holderview的帧大小。

有人能指出错误并指导我找到正确的解决方案吗？

Answer 1

您还可以使用函数updateConstraints。

[settingsView updateConstraints];

Answer 2

使用自动布局和更改框架属性会搞乱事情。

创建要更改或设置动画的约束的oultest

__weak IBOutlet UIView *settingsView;
__weak IBOutlet NSLayoutConstraint *settingsBottomConstraint;
__weak IBOutlet NSLayoutConstraint *settingsViewHeightConstraint;

更新约束（从不更新框架！）

settingsBottomConstraint.constant = - settingsViewHeightConstraint.constant;
[settingsView setNeedsUpdateConstraints];
[settingsView layoutIfNeeded];
isSettingsHidden = YES;

最近，我使用自动布局处理视图的动画，您可以在这里找到您的答案自动布局约束更改不会动画