UIStackView:从xib加载视图并更新subView的高度限制没有反映任何变化吗? [英] UIStackView: Loading views from xib and updating height constraint of subView did not reflecting any changes?

问题描述

我的应用程序中具有以下层次结构

I have the following hierarchy in my application

- UIScrollView
- UIStackView
 - UIView 1  // load with xib and added in arrangedSubviews
   - UIScrollView 1.1 // horizontal scrolling, fixed height constraint 38
   - UIView 1.2 // called it childView. has fixed height 0 (I load the view from xib and add it here dynamically and update its height)
     - UIView 1.2.1 // called it New View
 - UIView 2
 - UIView 3

所以我的问题是当我从xib加载视图并将其添加到UIView1.2时，也将高度限制0增加到了新添加的子视图的高度，但是什么也不会发生.UIView1.2 height预期不会更新.

So my problem is when I have loaded a view from xib and added it to UIView1.2 also increased height constraint 0 to a height of newly added sub-view but nothing will happen.UIView1.2height did not update expectedly .

self.constraintChildViewHeight.constant = 95;
[self layoutIfNeeded];

NewView *newView = (NewView *)[[[NSBundle mainBundle]loadNibNamed:NSStringFromClass([FieldPhotoView class]) owner:self options:nil]objectAtIndex:0];
[newView setTranslatesAutoresizingMaskIntoConstraints:false];
[self.childView addSubview:newView];
[self applyConstraintsToParent:self.childView andSubView:newView];

方法

- (void)applyConstraintsToParent:(UIView *)parentView andSubView:(UIView *)subView {
//constraints

NSLayoutConstraint *leading = [NSLayoutConstraint constraintWithItem:subView attribute:NSLayoutAttributeLeading relatedBy:NSLayoutRelationEqual toItem:parentView attribute:NSLayoutAttributeLeading multiplier:1.0 constant:0];

[parentView addConstraint:leading];

NSLayoutConstraint *trailing = [NSLayoutConstraint constraintWithItem:subView attribute:NSLayoutAttributeTrailing relatedBy:NSLayoutRelationEqual toItem:parentView attribute:NSLayoutAttributeTrailing multiplier:1.0 constant:0];


[parentView addConstraint:trailing];

NSLayoutConstraint *top = [NSLayoutConstraint constraintWithItem:subView attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:parentView attribute:NSLayoutAttributeTop multiplier:1.0 constant:0];

[parentView addConstraint:top];

NSLayoutConstraint *bottom = [NSLayoutConstraint constraintWithItem:subView attribute:NSLayoutAttributeBottom relatedBy:NSLayoutRelationEqual toItem:parentView attribute:NSLayoutAttributeBottom multiplier:1.0 constant:-8];

[parentView addConstraint:bottom];

NSLayoutConstraint *equalWidth = [NSLayoutConstraint constraintWithItem:subView attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:parentView attribute:NSLayoutAttributeWidth multiplier:1.0 constant:0];


[parentView addConstraint:equalWidth];

leading.active = true;
trailing.active = true;
top.active = true;
bottom.active = true;
equalWidth.active = true;
}

#Edit1-子视图约束

#Edit2 -为了更好地理解，我想使用xib(在UIStoryBoard中正常工作)以编程方式实现此功能.

#Edit2 - For better understanding, I want to achieve this functionality programmatically using xib's(In UIStoryBoard is just working fine.)

推荐答案

从您的问题中我了解到，您无法在scrollview 1.1中滚动内容.

From your question what i understood is that you are not able to scroll your content in the scrollview 1.1.

尝试以下步骤:

1. 对于滚动视图1.1

1. For the scrollview 1.1

• 使用View1给出顶部，底部，前导，尾随约束.
• 赋予scrollview高度限制= 38

对于子视图UIView 1.2

For the childview UIView 1.2

• 使用scrollview1.1给出顶部，底部，前导，尾随约束
• 使用View1固定子视图，以领先&后缘
• 赋予子视图高度限制
• 赋予子视图垂直居中约束.

对于newView UIView 1.2.1

For the newView UIView 1.2.1

• 从笔尖加载视图.
• 将其添加到子视图
• 设置其约束-顶部，底部，前导&尾随子视图.

这将使您的内容可滚动.

This will make your content scrollable.

我在这里共享了一个示例项目: https://github.com/Abhie87/StackExchangeSample

I have shared a sample project here: https://github.com/Abhie87/StackExchangeSample

希望这会有所帮助.

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