我想用高度,宽度的方式创建一个UILabel,然后我想通过编程方式添加约束来定位UILabel.
更新：
我想像这样创建UI：
如何创建这个UI所有程序
创建一个标签label1的代码类似地,我创建了两个label2和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];
现在我可以用这个代码添加水平约束
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-[label1]-|" options:NSLayoutFormatDirectionLeadingToTrailing metrics:nil views:NSDictionaryOfVariableBindings(label1)]];
我也可以设置垂直约束与视图,但我无法从一个标签到另一个标签设置约束.
解决方法
要创建高度和宽度约束的标签,这里是约束…不要忘了添加标签以查看与addSubview方法
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]];
和斯威夫特
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,constant: 200))
检查这个link更多的细节
UPDATE
当你更新你的问题,这是我更新的答案…
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