一，先上图

Public

对喽，我们今天的主角，就是图中标记的这四个文件。

这部分名字叫做Public，顾名思义，这部分给我们提供了简洁好用的，如系统API一样体验的方法。也是我们最常用的部分。

二，View+MASAdditions

这个是我最常用的部分。分类我们不用再提。我们直接看代码

///这个类前文有介绍，这里不多言。
#import "MASUtilities.h"
///这位，前文也有提到，就是我们的爱丽丝小姐。如果忘记了，请大家移步细致入微（二）。
///我们这个库是要干什么呢？对，将约束葛二蛋四兄弟添加到乔治身上。但并不是设置一个添加一个，而是收集完约束一块添加。那么问题来了，谁收集呢？哎，就是这位爱丽丝小姐收集。
#import "MASConstraintMaker.h"
///这个类之前我们有提到，但并没有深究。这里也不打算深究。但可以提一提。
/**这两行代码不知道你还有没有印象？这个newConstraint就是葛二蛋，viewAttribute持有了乔治和将要添加的约束。葛二蛋持有了viewAttribute。想想吧。
*MASViewAttribute *viewAttribute =
  [[MASViewAttribute alloc] initWithView:self.view
                         layoutAttribute:layoutAttribute];
*MASViewConstraint *newConstraint = 
  [[MASViewConstraint alloc] initWithFirstViewAttribute:viewAttribute];
*/
#import "MASViewAttribute.h"

/**
 *  Provides constraint maker block
 *  and convience methods for creating MASViewAttribute which are view + NSLayoutAttribute pairs
 */
@interface MAS_VIEW (MASAdditions)

/**
 *  following properties return a new MASViewAttribute with current view and appropriate     NSLayoutAttribute
 */
@property (nonatomic, strong, readonly) MASViewAttribute *mas_left;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_top;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_right;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_bottom;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_leading;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_trailing;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_width;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_height;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_centerX;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_centerY;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_baseline;
@property (nonatomic, strong, readonly) MASViewAttribute *(^mas_attribute)(NSLayoutAttribute attr);

@property (nonatomic, strong, readonly) MASViewAttribute *mas_firstBaseline;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_lastBaseline;

#if TARGET_OS_IPHONE || TARGET_OS_TV

@property (nonatomic, strong, readonly) MASViewAttribute *mas_leftMargin;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_rightMargin;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_topMargin;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_bottomMargin;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_leadingMargin;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_trailingMargin;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_centerXWithinMargins;
@property (nonatomic, strong, readonly) MASViewAttribute *mas_centerYWithinMargins;

@property (nonatomic, strong, readonly) MASViewAttribute *mas_safeAreaLayoutGuide NS_AVAILABLE_IOS(11.0);
@property (nonatomic, strong, readonly) MASViewAttribute *mas_safeAreaLayoutGuideLeading NS_AVAILABLE_IOS(11.0);
@property (nonatomic, strong, readonly) MASViewAttribute *mas_safeAreaLayoutGuideTrailing NS_AVAILABLE_IOS(11.0);
@property (nonatomic, strong, readonly) MASViewAttribute *mas_safeAreaLayoutGuideLeft NS_AVAILABLE_IOS(11.0);
@property (nonatomic, strong, readonly) MASViewAttribute *mas_safeAreaLayoutGuideRight NS_AVAILABLE_IOS(11.0);
@property (nonatomic, strong, readonly) MASViewAttribute *mas_safeAreaLayoutGuideTop NS_AVAILABLE_IOS(11.0);
@property (nonatomic, strong, readonly) MASViewAttribute *mas_safeAreaLayoutGuideBottom NS_AVAILABLE_IOS(11.0);
@property (nonatomic, strong, readonly) MASViewAttribute *mas_safeAreaLayoutGuideWidth NS_AVAILABLE_IOS(11.0);
@property (nonatomic, strong, readonly) MASViewAttribute *mas_safeAreaLayoutGuideHeight NS_AVAILABLE_IOS(11.0);
@property (nonatomic, strong, readonly) MASViewAttribute *mas_safeAreaLayoutGuideCenterX NS_AVAILABLE_IOS(11.0);
@property (nonatomic, strong, readonly) MASViewAttribute *mas_safeAreaLayoutGuideCenterY NS_AVAILABLE_IOS(11.0);

#endif


#pragma mark - --key--

/**
 *  a key to associate with this view
 */
@property (nonatomic, strong) id mas_key;

/**
 *  Finds the closest common superview between this view and another view
 *  查找此视图与另一个视图之间最近的公共超级视图
 *  @param  view    other view
 *
 *  @return returns nil if common superview could not be found
 */
- (instancetype)mas_closestCommonSuperview:(MAS_VIEW *)view;

/**
 *  Creates a MASConstraintMaker with the callee view.
 *  Any constraints defined are added to the view or the appropriate superview once the block has finished executing
 *
 *  @param block scope within which you can build up the constraints which you wish to apply to the view.
 *
 *  @return Array of created MASConstraints
 */
- (NSArray *)mas_makeConstraints:(void(NS_NOESCAPE ^)(MASConstraintMaker *make))block;

/**
 *  Creates a MASConstraintMaker with the callee view.
 *  Any constraints defined are added to the view or the appropriate superview once the block has finished executing.
 *  If an existing constraint exists then it will be updated instead.
 *
 *  @param block scope within which you can build up the constraints which you wish to apply to the view.
 *
 *  @return Array of created/updated MASConstraints
 */
- (NSArray *)mas_updateConstraints:(void(NS_NOESCAPE ^)(MASConstraintMaker *make))block;

/**
 *  Creates a MASConstraintMaker with the callee view.
 *  Any constraints defined are added to the view or the appropriate superview once the block has finished executing.
 *  All constraints previously installed for the view will be removed.
 *
 *  @param block scope within which you can build up the constraints which you wish to apply to the view.
 *
 *  @return Array of created/updated MASConstraints
 */
- (NSArray *)mas_remakeConstraints:(void(NS_NOESCAPE ^)(MASConstraintMaker *make))block;

@end