自动布局方法1
[NSLayoutConstraint constraintWithItem:(id)item
attribute:(NSLayoutAttribute)attribute
relatedBy:(NSLayoutRelation)relation
toItem:(id)otherItem
attribute:(NSLayoutAttribute)otherAttribute
multiplier:(CGFloat)multiplier
constant:(CGFloat)constant]
/*
* item 控件自己
* attribute 控件要约束的属性 NSLayoutAttributeLeft
* relatedBy 大于等于 小于等于 等于 NSLayoutRelationLessThanOrEqual
* toItem 相对控件
* attribute 相对控件的属性
* multiplier 乘以多少
* constant : 加上多少
* NSLayoutConstraint : 某个控件的属性值 等于 相对控件的属性值 乘以/加上 多少
* 添加约束 addConstraint
*/
例子
let blueView =UIView();
blueView.backgroundColor =UIColor.blueColor()
self.view.addSubview(blueView)//系统默认会给autoresizing 约束
// 关闭autoresizing 不关闭否则程序崩溃
blueView.translatesAutoresizingMaskIntoConstraints =false
//宽度约束
let width:NSLayoutConstraint = NSLayoutConstraint(item: blueView,
attribute: NSLayoutAttribute.Width,
relatedBy:NSLayoutRelation.Equal,
toItem:nil,
attribute: NSLayoutAttribute.NotAnAttribute,
multiplier:0.0,
constant:200)
blueView.addConstraint(width)//自己添加约束
//高度约束
let height:NSLayoutConstraint = NSLayoutConstraint(item: blueView,
attribute: NSLayoutAttribute.Height,
relatedBy:NSLayoutRelation.Equal,
toItem:nil,
attribute: NSLayoutAttribute.NotAnAttribute,
multiplier:0.0,
constant:200)
blueView.addConstraint(height)//自己添加约束
//右边约束
let right:NSLayoutConstraint = NSLayoutConstraint(item: blueView,
attribute: NSLayoutAttribute.Right,
relatedBy:NSLayoutRelation.Equal,
toItem:self.view,
attribute:NSLayoutAttribute.Right,
multiplier:1.0,
constant: -20)
blueView.superview!.addConstraint(right)//父控件添加约束
//下边约束
let bottom:NSLayoutConstraint = NSLayoutConstraint(item: blueView,
attribute: NSLayoutAttribute.Bottom,
relatedBy:NSLayoutRelation.Equal,
toItem:self.view,
attribute:NSLayoutAttribute.Bottom,
multiplier:1.0,
constant: -20)
blueView.superview!.addConstraint(bottom)//父控件添加约束
例子2
- (void)createThreeViews{
//1 创建3个view的对象
UIView *leftView = [[UIView alloc]init];
UIView *rightView = [[UIView alloc]init];
UIView *bottomView = [[UIView alloc]init];
//2 设置背景颜色
leftView.backgroundColor = [UIColor greenColor];
rightView.backgroundColor = [UIColor purpleColor];
bottomView.backgroundColor = [UIColor orangeColor];
//3 添加视图上显示
[self.view addSubview:leftView];
[self.view addSubview:rightView];
[self.view addSubview:bottomView];
//4 关闭系统的自定义布局
leftView.translatesAutoresizingMaskIntoConstraints = NO;
rightView.translatesAutoresizingMaskIntoConstraints = NO;
bottomView.translatesAutoresizingMaskIntoConstraints = NO;
//leftView的上 = self.view的上+20
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:leftView
attribute:NSLayoutAttributeTop
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeTop
multiplier:1.
constant:20]];
// leftView的左 = self.view的左 + 20
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:leftView
attribute:NSLayoutAttributeLeft
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeLeft
multiplier:1.
constant:20]];
// rightView的上 = leftView的上
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:rightView
attribute:NSLayoutAttributeTop
relatedBy:NSLayoutRelationEqual
toItem:leftView
attribute:NSLayoutAttributeTop
multiplier:1.
constant:0]];
// rightView的左 = leftView的右 + 20
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:rightView
attribute:NSLayoutAttributeLeft
relatedBy:NSLayoutRelationEqual
toItem:leftView
attribute:NSLayoutAttributeRight
multiplier:1.
constant:20]];
// rightView的右 = self.view的右 - 20
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:rightView
attribute:NSLayoutAttributeRight
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeRight
multiplier:1.
constant:-20]];
// rightView的高 = leftView的高
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:rightView
attribute:NSLayoutAttributeHeight
relatedBy:NSLayoutRelationEqual
toItem:leftView
attribute:NSLayoutAttributeHeight
multiplier:1.
constant:0]];
// rightView的宽 = leftView的宽
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:rightView
attribute:NSLayoutAttributeWidth
relatedBy:NSLayoutRelationEqual
toItem:leftView
attribute:NSLayoutAttributeWidth
multiplier:1.0
constant:0]];
//bottomView的左 = self.view的左 + 20
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:bottomView
attribute:NSLayoutAttributeLeft
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeLeft
multiplier:1
constant:20]];
//bottomView的右 = self.view的右 - 20
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:bottomView
attribute:NSLayoutAttributeRight
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeRight
multiplier:1
constant:-20]];
//bottomView的上 = leftView的下 + 20
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:bottomView
attribute:NSLayoutAttributeTop
relatedBy:NSLayoutRelationEqual
toItem:leftView
attribute:NSLayoutAttributeBottom
multiplier:1
constant:20]];
//bottomView的高 = leftView的高
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:bottomView
attribute:NSLayoutAttributeHeight
relatedBy:NSLayoutRelationEqual
toItem:leftView
attribute:NSLayoutAttributeHeight
multiplier:1
constant:0]];
//bottomView的下 = self.view的下 + 20
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:bottomView
attribute:NSLayoutAttributeBottom
relatedBy:NSLayoutRelationEqual
toItem:self.view
attribute:NSLayoutAttributeBottom
multiplier:1
constant:-20]];
自动布局方法2
NSArray *constrArray = [NSLayoutConstraint constraintsWithVisualFormat:@"string类型"
options:
metrics:
views:]；
/*
1. 自动布局使用可视化语言:VFL(Visual Format Language)
2. 自动布局的相关参数
3. 解释：
a) 第一个参数：使用VFL格式化的字符串，可以参见官方的帮助文档；
b) 第二个参数：指定VFL中所有对象的布局属性和方向。举例：有2个视图使用VFL进行布局，可以使用NSLayoutFormatAlignAllLeft，就让两个视图左对齐；
c) 第三个参数：度量或者指标的字典，字典里面有相关的键值对来控制相关的度量指标，通过key获取；
d) 第四个参数：指定约束的视图：一个或多个。
4. VFL语言的规则
a) "H" 表示水平方向，"V"表示垂直方向；
b) "|" 表示superview的边界；
c) "[]" 表示view，"()"表示尺寸，它们可以多个条件组合，中间使用逗号分隔，举例：[view(>=70, <=100)];
d) "-" 表示间隙；
e) "@"表示优先级。举例：V:|-50@750-[view(55)]
*/
/**
//创建VFL约束字符串
NSString *hVFL = @"H:|-space-[leftView(==rightView)]-space1-[rightView]-space-|";
NSString *hVFL1 = @"H:|-space-[bottomView]-space-|";
NSString *vVFL = @"V:|-space-[leftView(==bottomView)]-space-[bottomView]-space-|";
NSString *vVFL1 = @"V:|-space-[rightView(==bottomView)]-space-[bottomView]-space-|";
//创建键值映射
NSDictionary *metircs = @{@"space":@20,@"space1":@30};
NSDictionary *views = NSDictionaryOfVariableBindings(leftView,rightView,bottomView);
//创建约束
NSArray *hconstraint = [NSLayoutConstraint constraintsWithVisualFormat:hVFL
options:NSLayoutFormatDirectionLeadingToTrailing
metrics:metircs
views:views];
NSArray *hconstraint1 = [NSLayoutConstraint constraintsWithVisualFormat:hVFL1
options:NSLayoutFormatDirectionLeadingToTrailing
metrics:metircs
views:views];
NSArray *vconstraint = [NSLayoutConstraint constraintsWithVisualFormat:vVFL
options:NSLayoutFormatDirectionLeadingToTrailing
metrics:metircs
views:views];
NSArray *vconstraint1 = [NSLayoutConstraint constraintsWithVisualFormat:vVFL1
options:NSLayoutFormatDirectionLeadingToTrailing
metrics:metircs
views:views];
//添加约束
[self.view addConstraints:hconstraint];
[self.view addConstraints:hconstraint1];
[self.view addConstraints:vconstraint];
[self.view addConstraints:vconstraint1];
