苹果自带的自动布局AutoLayout实现方式令人望而生畏，但还是包含着不错的思想，有人封装了第三方Masonry，试了试，感觉不错。
Masonry 点击获取Masonry第三方SDK
下载完Masonry后，导入Masonry框架，有两种方式 CocoaPod或者直接拖拽添加到资源项目文件中，删除Masonry文件夹内的plist文件，防止冲突。
Masonry对AutoLayout做了比较精简的封装，是的对视图的约束条件更加的简洁明确，布局目标一目了然，非常不错。
三个核心的方法如下
添加约束
- (NSArray *)mas_makeConstraints:(void(^)(MASConstraintMaker *))block {
}
更新约束
- (NSArray *)mas_updateConstraints:(void(^)(MASConstraintMaker *))block {
}
重写约束
- (NSArray *)mas_remakeConstraints:(void(^)(MASConstraintMaker *make))block {
}
//以下是常用的属性
@property (nonatomic, strong, readonly) MASConstraint *left; //左侧
@property (nonatomic, strong, readonly) MASConstraint *top; //上侧
@property (nonatomic, strong, readonly) MASConstraint *right; //右侧
@property (nonatomic, strong, readonly) MASConstraint *bottom; //下侧
@property (nonatomic, strong, readonly) MASConstraint *leading; //首部
@property (nonatomic, strong, readonly) MASConstraint *trailing; //尾部
@property (nonatomic, strong, readonly) MASConstraint *width; //宽
@property (nonatomic, strong, readonly) MASConstraint *height; //高
@property (nonatomic, strong, readonly) MASConstraint *centerX; //横向居中
@property (nonatomic, strong, readonly) MASConstraint *centerY; //纵向居中
@property (nonatomic, strong, readonly) MASConstraint *baseline; //文本基线
//以下是常用的关系比较函数（ 大于等于，小于等于，等于）
- (MASConstraint * (^)(id))equalTo {
return ^id(id attribute) {
return self.equalToWithRelation(attribute, NSLayoutRelationEqual);
};
}
- (MASConstraint * (^)(id))mas_equalTo {
return ^id(id attribute) {
return self.equalToWithRelation(attribute, NSLayoutRelationEqual);
};
}
- (MASConstraint * (^)(id))greaterThanOrEqualTo {
return ^id(id attribute) {
return self.equalToWithRelation(attribute, NSLayoutRelationGreaterThanOrEqual);
};
}
- (MASConstraint * (^)(id))mas_greaterThanOrEqualTo {
return ^id(id attribute) {
return self.equalToWithRelation(attribute, NSLayoutRelationGreaterThanOrEqual);
};
}
- (MASConstraint * (^)(id))lessThanOrEqualTo {
return ^id(id attribute) {
return self.equalToWithRelation(attribute, NSLayoutRelationLessThanOrEqual);
};
}
- (MASConstraint * (^)(id))mas_lessThanOrEqualTo {
return ^id(id attribute) {
return self.equalToWithRelation(attribute, NSLayoutRelationLessThanOrEqual);
};
}
其实还有很多东西，想要全面了解，还是看SDK源代码比较好
下面是简单的使用示例，想要更多的了解，亲自试验是王道。
UIView *v1=[[UIView alloc]init];
v1.backgroundColor=[UIColor redColor];
[self.view addSubview:v1];
__weak __typeof(&*self)weakSelf = self;//防止循环引用
//设置v1视图红色并且长宽各100，位于父视图色self.view中心
[v1 mas_makeConstraints:^(MASConstraintMaker* make){
make.size.mas_equalTo(CGSizeMake(100, 100));
make.center.equalTo(weakSelf.view);
}];
UIView *v1=[[UIView alloc]init];
v1.backgroundColor=[UIColor redColor];
[self.view addSubview:v1];
UIView *v2=[[UIView alloc]init];
v2.backgroundColor=[UIColor greenColor];
[self.view addSubview:v2];
__weak __typeof(&*self)weakSelf = self;
//设置v1视图红色并且长宽各100，位于父视图色self.view中心
[v1 mas_makeConstraints:^(MASConstraintMaker* make){
make.size.mas_equalTo(CGSizeMake(100, 100));
make.center.equalTo(weakSelf.view);
}];
//设置视图v2绿色并且距离父视图上左右各100，高度不超过100
[v2 mas_makeConstraints:^(MASConstraintMaker* make){
make.top.mas_equalTo(weakSelf.view).offset(100);
make.left.mas_equalTo(weakSelf.view).offset(100);
make.right.mas_equalTo(weakSelf.view).offset(-100);
make.height.mas_equalTo(@100);
}];
