如何以编程方式创建布局约束 [英] How to Create layout constraints programmatically

问题描述

我在通用应用程序的底部显示一个视图，并在我的视图中动态添加此视图。我想显示这个视图在底部每次像iAd。在两个方向。如何为此添加约束。请建议。

感谢

解决方案

您需要以下约束来设置屏幕底部。

1. 领先约束< 宽度

的父视图 X

2. < - >
3. 高度约束
   
   
   pre> UIView * subView = bottomView;
UIView * parent = self.view;

subView.translatesAutoresizingMaskIntoConstraints = NO;

// Trailing
NSLayoutConstraint * trailing = [NSLayoutConstraint
constraintWithItem：subView
attribute：NSLayoutAttributeTrailing
relatedBy：NSLayoutRelationEqual
toItem：parent
attribute：NSLayoutAttributeTrailing
multiplier：1.0f
常数：0.f];

//前导

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

// Bottom
NSLayoutConstraint * bottom = [NSLayoutConstraint
constraintWithItem：subView
attribute：NSLayoutAttributeBottom
relatedBy：NSLayoutRelationEqual
toItem：parent
attribute：NSLayoutAttributeBottom
multiplier：1.0f
常数：0.f];

//与AdHeight一样的SubView的固定高度
NSLayoutConstraint * height = [NSLayoutConstraint
constraintWithItem：subView
attribute：NSLayoutAttributeHeight
relatedBy：NSLayoutRelationEqual
toItem：nil
attribute：NSLayoutAttributeNotAnAttribute
multiplier：0
常数：ADHeight];


[parent addConstraint：trailing];
[parent addConstraint：bottom];
[parent addConstraint：leading];

[subView addConstraint：height];


   希望这有助。

   
   
   
   
   

   I am displaying a view in the bottom of the universal application and adding this view dynamically in my view. I want to show this view in bottom every time like iAd. in both orientation. How can I add constraints for this. Please suggest.

   Thanks

   解决方案

   To fix a view to the bottom of the screen you need following constraints to set.

   1. Leading Constraint with respect of Parent View for - X
   2. Trailing Constraint with respect of Parent View for - Width
   3. Bottom Constraint with respect of Parent View for - Y
   4. Height Constraint attached to self for - Height.

   Lets add.

   UIView *subView=bottomView;
   UIView *parent=self.view;
   
   subView.translatesAutoresizingMaskIntoConstraints = NO;
   
   //Trailing    
   NSLayoutConstraint *trailing =[NSLayoutConstraint
                                   constraintWithItem:subView
                                   attribute:NSLayoutAttributeTrailing
                                   relatedBy:NSLayoutRelationEqual
                                   toItem:parent   
                                   attribute:NSLayoutAttributeTrailing
                                   multiplier:1.0f
                                   constant:0.f];
   
   //Leading
   
   NSLayoutConstraint *leading = [NSLayoutConstraint
                                      constraintWithItem:subView
                                      attribute:NSLayoutAttributeLeading
                                      relatedBy:NSLayoutRelationEqual
                                      toItem:parent
                                      attribute:NSLayoutAttributeLeading
                                      multiplier:1.0f
                                      constant:0.f];
   
   //Bottom
   NSLayoutConstraint *bottom =[NSLayoutConstraint
                                    constraintWithItem:subView
                                    attribute:NSLayoutAttributeBottom
                                    relatedBy:NSLayoutRelationEqual
                                    toItem:parent
                                    attribute:NSLayoutAttributeBottom
                                    multiplier:1.0f
                                    constant:0.f];
   
   //Height to be fixed for SubView same as AdHeight
   NSLayoutConstraint *height = [NSLayoutConstraint
                                  constraintWithItem:subView
                                  attribute:NSLayoutAttributeHeight
                                  relatedBy:NSLayoutRelationEqual
                                  toItem:nil
                                  attribute:NSLayoutAttributeNotAnAttribute
                                  multiplier:0
                                  constant:ADHeight];
   
   
       [parent addConstraint:trailing];
       [parent addConstraint:bottom];
       [parent addConstraint:leading];
   
       [subView addConstraint:height];
   

   Hope this helps.

   Cheers.

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