IOS学习 autolayout 自动布局 代码与界面设置截图

- (void)viewDidLoad {

[super
viewDidLoad];

// Do any additional setup after loading the view.

UIView *blueView = [[UIView
alloc]init];
//不用设置Frame

blueView.backgroundColor = [UIColor
blueColor];

[self.view
addSubview:blueView];

//一定要把View的autoresizing属性禁掉

blueView.translatesAutoresizingMaskIntoConstraints =
NO;

/*

constraintWithItem: 被约束的view

attribute: 被约束的view的属性

relatedBy:设置与参考View的关系

NSLayoutRelationLessThanOrEqual = -1, 小于等于

NSLayoutRelationEqual = 0, 等于

NSLayoutRelationGreaterThanOrEqual = 1,大于等于

toItem: 参照的view

attribute: 参照的view的属性**/

//添加blueView的顶部约束

NSLayoutConstraint *blueTop = [NSLayoutConstraint

constraintWithItem:blueView

attribute:NSLayoutAttributeTop

relatedBy:NSLayoutRelationEqual

toItem:self.view

attribute:NSLayoutAttributeTop

multiplier:1

constant:20];

//把约束添加到控制的父view上

[self.view
addConstraint:blueTop];

//添加blueView的左侧约束

NSLayoutConstraint *blueLeft = [NSLayoutConstraint

constraintWithItem:blueView

attribute:NSLayoutAttributeLeft

relatedBy:NSLayoutRelationEqual

toItem:self.view

attribute:NSLayoutAttributeLeft

multiplier:1

constant:20];

[self.view
addConstraint:blueLeft];

//添加blueView的右侧约束

NSLayoutConstraint *blueRight = [NSLayoutConstraint

constraintWithItem:blueView

attribute:NSLayoutAttributeRight

relatedBy:NSLayoutRelationEqual

toItem:self.view
attribute:NSLayoutAttributeRight

multiplier:1

constant:-20];

[self.view
addConstraint:blueRight];

//添加blueView的高度约束

NSLayoutConstraint *blueHeight = [NSLayoutConstraint

constraintWithItem:blueView

attribute:NSLayoutAttributeHeight

relatedBy:NSLayoutRelationEqual

toItem:nil
//没有参照

attribute:NSLayoutAttributeNotAnAttribute

multiplier:1

constant:50];

//高和宽没有参照的约束添加到父view和本身blueView上，都可以

[self.view
addConstraint:blueHeight];

// [blueView addConstraint:blueHeight];

UIView *redView = [[UIView
alloc]init];

redView.backgroundColor = [UIColor
redColor];

[self.view
addSubview:redView];

redView.translatesAutoresizingMaskIntoConstraints =
NO;

//添加redView的顶部约束

NSLayoutConstraint *redTop = [NSLayoutConstraint

constraintWithItem:redView

attribute:NSLayoutAttributeTop
//顶部

relatedBy:NSLayoutRelationEqual

toItem:blueView

attribute:NSLayoutAttributeBottom
//底部

multiplier:1

constant:20];

//把约束添加到控制的父view上

[self.view
addConstraint:redTop];

//添加redView的右侧约束

NSLayoutConstraint *redRight= [NSLayoutConstraint

constraintWithItem:redView

attribute:NSLayoutAttributeTrailing
//尾部对齐

relatedBy:NSLayoutRelationEqual

toItem:blueView

attribute:NSLayoutAttributeTrailing
//尾部对齐

multiplier:1

constant:0];

[self.view
addConstraint:redRight];

//添加redView的高度约束

NSLayoutConstraint *redHeight = [NSLayoutConstraint

constraintWithItem:redView

attribute:NSLayoutAttributeHeight

relatedBy:NSLayoutRelationEqual

toItem:blueView

attribute:NSLayoutAttributeHeight

multiplier:1

constant:0];

[self.view
addConstraint:redHeight];

//添加redView的宽度约束

NSLayoutConstraint *redWidth = [NSLayoutConstraint

constraintWithItem:redView

attribute:NSLayoutAttributeWidth

relatedBy:NSLayoutRelationEqual

toItem:blueView

attribute:NSLayoutAttributeWidth

multiplier:0.5

constant:0];

[self.view
addConstraint:redWidth];

}