iOS masonry的使用方法

platform :ios, '7.0'
target 'test2' do
pod 'Masonry'
end
//target后面的单引号里是你工程的名字

/添加新约束

- (NSArray *)mas_makeConstraints:(void(NS_NOESCAPE ^)(MASConstraintMaker *make))block;

//更新约束，会覆盖之前的约束

- (NSArray *)mas_updateConstraints:(void(NS_NOESCAPE ^)(MASConstraintMaker *make))block;

//完全移除旧约束，添加新约束（重置）

- (NSArray *)mas_remakeConstraints:(void(NS_NOESCAPE ^)(MASConstraintMaker *make))block;

equalTo()       参数是对象类型，一般是视图对象或者mas_width这样的坐标系对象
mas_equalTo()   和上面功能相同，参数可以传递基础数据类型对象，可以理解为比上面的API更强大

width()         用来表示宽度，例如代表view的宽度
mas_width()     用来获取宽度的值。和上面的区别在于，一个代表某个坐标系对象，一个用来获取坐标系对象的值

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    UILabel* label = [[UILabel alloc] init];
    [self.view addSubview:label];
    [label mas_makeConstraints:^(MASConstraintMaker *make) {
        make.centerX.equalTo(self.view);
                            make.top.equalTo(self.view).offset(100);
                             make.size.mas_equalTo(CGSizeMake(200, 50));
    }];
    label.backgroundColor = [UIColor blackColor];
    UIButton* button = [UIButton buttonWithType:UIButtonTypeCustom];
    [self.view addSubview:button];
    [button mas_makeConstraints:^(MASConstraintMaker *make) {
        make.centerX.equalTo(label);
        make.top.equalTo(label.mas_bottom).offset(100);
        make.size.mas_equalTo(CGSizeMake(200, 50));
    }];
    [button setBackgroundColor:[UIColor yellowColor]];
    [button setTitle:@"更新约束" forState:UIControlStateNormal];
    [button addTarget:self action:@selector(press:) forControlEvents:UIControlEventTouchUpInside];
    [button setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
}

-(void) press:(UIButton*) btn {
    [btn mas_updateConstraints:^(MASConstraintMaker *make) {
        make.size.mas_equalTo(CGSizeMake(100, 100));
    }];
}