如何以编程方式仅设置UILabel的宽度和高度以及约束 [英] How to set UILabel only width and height and constraints programmatically

问题描述

我想以编程方式使用高度，宽度创建UILabel，然后我想以编程方式为其添加约束以定位UILabel。

I want to create a UILabel programmatically with height, width and then I want to add constraints to it also programmatically for positioning the UILabel.

更新：

我想像这样创建UI：

如何以编程方式创建此UI

创建一个标签的代码 label1 同样我又创建了两个标签 label2 和 label3

Code to create one label label1 similarly I created two more label label2 and label3

UILabel *label1 = [[UILabel alloc]init];

label1.font = TitleFont;
label1.numberOfLines=0;
label1.text= @"Descriptions";
label1.lineBreakMode=NSLineBreakByWordWrapping;
[label1 sizeToFit];
label1.backgroundColor=[UIColor blueColor];
label1.textColor=[UIColor blackColor];
label1.translatesAutoresizingMaskIntoConstraints = NO;
[self.view addSubview:label1];

现在我可以使用此代码添加水平约束

And now I am able to add horizontal constraints them with this code

[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-[label1]-|" options:NSLayoutFormatDirectionLeadingToTrailing metrics:nil views:NSDictionaryOfVariableBindings(label1)]];

我也能用视图设置垂直约束但我无法用一个标签设置约束另一个。

I am also able to set vertical constraint with view but I am unable to set constraint with from one label to another.

推荐答案

要创建具有高度和宽度约束的标签，这里是约束...并且不要忘记添加标签用查看addSubview 方法

To create label with height and width constraints here is the constraints...And don't forget to add label in to view with addSubview method

UILabel *Label = [[UILabel alloc] init];
[Label setTranslatesAutoresizingMaskIntoConstraints:NO];  

[self.view addSubview:Label];

// Width constraint
[Label addConstraint:[NSLayoutConstraint constraintWithItem:Label
                                                      attribute:NSLayoutAttributeWidth
                                                      relatedBy:NSLayoutRelationEqual
                                                         toItem:nil
                                                      attribute: NSLayoutAttributeNotAnAttribute
                                                     multiplier:1
                                                       constant:200]];

// Height constraint
[Label addConstraint:[NSLayoutConstraint constraintWithItem:Label
                                                      attribute:NSLayoutAttributeHeight
                                                      relatedBy:NSLayoutRelationEqual
                                                         toItem:nil
                                                      attribute: NSLayoutAttributeNotAnAttribute
                                                     multiplier:1
                                                       constant:21]];

并且在Swift中

 Label.setTranslatesAutoresizingMaskIntoConstraints(false)
 self.view.addSubview(Label)

 Label.addConstraint(NSLayoutConstraint(item: Label, attribute: .Height, relatedBy: .Equal, toItem: nil, attribute: .NotAnAttribute, multiplier: 1, constant: 21))
 Label.addConstraint(NSLayoutConstraint(item: Label, attribute: .Width, relatedBy: .Equal, toItem: nil, attribute: .NotAnAttribute, multiplier: 1, constant: 200))  

检查这个link 了解更多详情

UPDATE

当您更新问题时，这是我更新的答案...

UPDATE
As you update your question, here is my updated answer...

UILabel *Label1 = [[UILabel alloc] init];
[Label1 setTranslatesAutoresizingMaskIntoConstraints:NO];
UILabel *Label2 = [[UILabel alloc] init];
[Label2 setTranslatesAutoresizingMaskIntoConstraints:NO];

Label1.text = @"Label1";
Label1.backgroundColor = [UIColor blueColor];
Label2.text = @"Label2";
Label2.backgroundColor = [UIColor redColor];

[self.view addSubview:Label1];
[self.view addSubview:Label2];

// Width constraint
[Label1 addConstraint:[NSLayoutConstraint constraintWithItem:Label1
                                                  attribute:NSLayoutAttributeWidth
                                                  relatedBy:NSLayoutRelationEqual
                                                     toItem:nil
                                                  attribute: NSLayoutAttributeNotAnAttribute
                                                 multiplier:1
                                                   constant:280]];

// Height constraint
[Label1 addConstraint:[NSLayoutConstraint constraintWithItem:Label1
                                                  attribute:NSLayoutAttributeHeight
                                                  relatedBy:NSLayoutRelationEqual
                                                     toItem:nil
                                                  attribute: NSLayoutAttributeNotAnAttribute
                                                 multiplier:1
                                                   constant:21]];

// CenterX constraint
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:self.view
                                                   attribute:NSLayoutAttributeCenterX
                                                   relatedBy:NSLayoutRelationEqual
                                                      toItem:Label1
                                                   attribute: NSLayoutAttributeCenterX
                                                  multiplier:1
                                                    constant:0]];
// Top constraint
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:Label1
                                                      attribute:NSLayoutAttributeTop
                                                      relatedBy:NSLayoutRelationEqual
                                                         toItem:self.topLayoutGuide
                                                      attribute: NSLayoutAttributeBottom
                                                     multiplier:1
                                                       constant:40]];


// label2
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:Label1
                                                      attribute:NSLayoutAttributeLeading
                                                      relatedBy:NSLayoutRelationEqual
                                                         toItem:Label2
                                                      attribute: NSLayoutAttributeLeading
                                                     multiplier:1
                                                       constant:0]];
// label2.Height = label1.Height
[self.view  addConstraint:[NSLayoutConstraint constraintWithItem:Label1
                                                      attribute:NSLayoutAttributeHeight
                                                      relatedBy:NSLayoutRelationEqual
                                                         toItem:Label2
                                                      attribute: NSLayoutAttributeHeight
                                                     multiplier:1
                                                       constant:0]];
// label2.width = label1.width
[self.view  addConstraint:[NSLayoutConstraint constraintWithItem:Label1
                                                   attribute:NSLayoutAttributeWidth
                                                   relatedBy:NSLayoutRelationEqual
                                                      toItem:Label2
                                                   attribute: NSLayoutAttributeWidth
                                                  multiplier:1
                                                    constant:0]];

// label2.Top
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:Label2
                                                      attribute:NSLayoutAttributeTop
                                                      relatedBy:NSLayoutRelationEqual
                                                         toItem:Label1
                                                      attribute: NSLayoutAttributeBottom
                                                     multiplier:1
                                                       constant:34]];  

结果屏幕

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