IOS AutoLayout学习

Autolayout


一、NSLayoutConstraint类

//偏移量
@property CGFloat constant;


//优先级
@property UILayoutPriority priority;

//"view1.attr1 = view2.attr2 * multiplier + constant" 
+(id)constraintWithItem:(id)view1 attribute:(NSLayoutAttribute)attr1 relatedBy:(NSLayoutRelation)relation toItem:(id)view2 attribute:(NSLayoutAttribute)attr2 multiplier:(CGFloat)multiplier constant:(CGFloat)c;

typedef NS_ENUM(NSInteger, NSLayoutRelation) {
    NSLayoutRelationLessThanOrEqual = -1,          //小于等于
    NSLayoutRelationEqual = 0,                     //等于
    NSLayoutRelationGreaterThanOrEqual = 1,        //大于等于
};
typedef NS_ENUM(NSInteger, NSLayoutAttribute) 
{
    NSLayoutAttributeLeft = 1,                     //左侧
    NSLayoutAttributeRight,                        //右侧
    NSLayoutAttributeTop,                          //上方
    NSLayoutAttributeBottom,                       //下方
    NSLayoutAttributeLeading,                      //首部
    NSLayoutAttributeTrailing,                     //尾部
    NSLayoutAttributeWidth,                        //宽度
    NSLayoutAttributeHeight,                       //高度
    NSLayoutAttributeCenterX,                      //X轴中心
    NSLayoutAttributeCenterY,                      //Y轴中心
    NSLayoutAttributeBaseline,                     //文本底标线

    NSLayoutAttributeNotAnAttribute = 0            //没有属性
};


二、IOS6后UIView添加的约束类别

//Default YES 标示是否自动遵循视图布局约束
- (BOOL)translatesAutoresizingMaskIntoConstraints NS_AVAILABLE_IOS(6_0);

//设置是否自动遵循视图布局约束
- (void)setTranslatesAutoresizingMaskIntoConstraints:(BOOL)flag NS_AVAILABLE_IOS(6_0);

//返回是遵循自定义视图布局约束
+ (BOOL)requiresConstraintBasedLayout NS_AVAILABLE_IOS(6_0);