image.png

1、UIView

@property (nonatomic) UIEdgeInsets layoutMargins NS_AVAILABLE_IOS(8_0);
@property (nonatomic) NSDirectionalEdgeInsets directionalLayoutMargins API_AVAILABLE(ios(11.0),tvos(11.0));

@property (nonatomic) BOOL preservesSuperviewLayoutMargins NS_AVAILABLE_IOS(8_0);
@property (nonatomic) BOOL insetsLayoutMarginsFromSafeArea API_AVAILABLE(ios(11.0),tvos(11.0));  // Default: YES

- (void)layoutMarginsDidChange NS_AVAILABLE_IOS(8_0);



@property (nonatomic,readonly) UIEdgeInsets safeAreaInsets API_AVAILABLE(ios(11.0),tvos(11.0));
- (void)safeAreaInsetsDidChange API_AVAILABLE(ios(11.0),tvos(11.0));


@property(readonly,strong) UILayoutGuide *layoutMarginsGuide NS_AVAILABLE_IOS(9_0);
@property (nonatomic, readonly, strong) UILayoutGuide *readableContentGuide  NS_AVAILABLE_IOS(9_0);
@property(nonatomic,readonly,strong) UILayoutGuide *safeAreaLayoutGuide API_AVAILABLE(ios(11.0),tvos(11.0));

self.view.layoutMargins= {40, 20, 0, 20}, self.view.directionalLayoutMargins= {40, 20, 0, 20}
self.view.insetsLayoutMarginsFromSafeArea = true

SafeAreaLayoutGuide 没有开启SafeAreaLayoutGuides同样可以设置Margins ----SafeAreaRelatvieMargins
SafeAreaRelatvieMargins

UILayoutGuide iOS 9可用。

NS_CLASS_AVAILABLE_IOS(9_0)
@interface UILayoutGuide : NSObject <NSCoding>

@property(nonatomic,readonly) CGRect layoutFrame;


@property(nonatomic,weak,nullable) UIView *owningView;

@property(nonatomic,copy) NSString *identifier;


@property(nonatomic,readonly,strong) NSLayoutXAxisAnchor *leadingAnchor;
@property(nonatomic,readonly,strong) NSLayoutXAxisAnchor *trailingAnchor;
@property(nonatomic,readonly,strong) NSLayoutXAxisAnchor *leftAnchor;
@property(nonatomic,readonly,strong) NSLayoutXAxisAnchor *rightAnchor;
@property(nonatomic,readonly,strong) NSLayoutYAxisAnchor *topAnchor;
@property(nonatomic,readonly,strong) NSLayoutYAxisAnchor *bottomAnchor;
@property(nonatomic,readonly,strong) NSLayoutDimension *widthAnchor;
@property(nonatomic,readonly,strong) NSLayoutDimension *heightAnchor;
@property(nonatomic,readonly,strong) NSLayoutXAxisAnchor *centerXAnchor;
@property(nonatomic,readonly,strong) NSLayoutYAxisAnchor *centerYAnchor;

@end




@interface UIView (UILayoutGuideSupport)
@property(nonatomic,readonly,copy) NSArray<__kindof UILayoutGuide *> *layoutGuides NS_AVAILABLE_IOS(9_0);
- (void)addLayoutGuide:(UILayoutGuide *)layoutGuide NS_AVAILABLE_IOS(9_0);
- (void)removeLayoutGuide:(UILayoutGuide *)layoutGuide NS_AVAILABLE_IOS(9_0);
@end

2、UIViewController

@interface UIViewController (UILayoutSupport)

@property(nonatomic,readonly,strong) id<UILayoutSupport> topLayoutGuide API_DEPRECATED_WITH_REPLACEMENT("-[UIView safeAreaLayoutGuide]", ios(7.0,11.0), tvos(7.0,11.0));
@property(nonatomic,readonly,strong) id<UILayoutSupport> bottomLayoutGuide API_DEPRECATED_WITH_REPLACEMENT("-[UIView safeAreaLayoutGuide]", ios(7.0,11.0), tvos(7.0,11.0));


@property(nonatomic) UIEdgeInsets additionalSafeAreaInsets API_AVAILABLE(ios(11.0), tvos(11.0));

@property(nonatomic,readonly) NSDirectionalEdgeInsets systemMinimumLayoutMargins API_AVAILABLE(ios(11.0), tvos(11.0));


@property(nonatomic) BOOL viewRespectsSystemMinimumLayoutMargins API_AVAILABLE(ios(11.0), tvos(11.0));

- (void)viewLayoutMarginsDidChange NS_REQUIRES_SUPER API_AVAILABLE(ios(11.0), tvos(11.0));
- (void)viewSafeAreaInsetsDidChange NS_REQUIRES_SUPER API_AVAILABLE(ios(11.0), tvos(11.0));





@property(nonatomic,assign) BOOL wantsFullScreenLayout NS_DEPRECATED_IOS(3_0, 7_0) __TVOS_PROHIBITED; // Deprecated in 7_0, Replaced by the following:

@property(nonatomic,assign) UIRectEdge edgesForExtendedLayout NS_AVAILABLE_IOS(7_0); // Defaults to UIRectEdgeAll
@property(nonatomic,assign) BOOL extendedLayoutIncludesOpaqueBars NS_AVAILABLE_IOS(7_0); // Defaults to NO, but bars are translucent by default on 7_0.  
@property(nonatomic,assign) BOOL automaticallyAdjustsScrollViewInsets API_DEPRECATED_WITH_REPLACEMENT("Use UIScrollView's contentInsetAdjustmentBehavior instead", ios(7.0,11.0),tvos(7.0,11.0)); // Defaults to YES





@protocol UILayoutSupport <NSObject>
@property(nonatomic,readonly) CGFloat length;  

@property(readonly, strong) NSLayoutYAxisAnchor *topAnchor NS_AVAILABLE_IOS(9_0);
@property(readonly, strong) NSLayoutYAxisAnchor *bottomAnchor NS_AVAILABLE_IOS(9_0);
@property(readonly, strong) NSLayoutDimension *heightAnchor NS_AVAILABLE_IOS(9_0);
@end

3、 UIScrollView

@property(nonatomic, readonly) UIEdgeInsets adjustedContentInset API_AVAILABLE(ios(11.0),tvos(11.0));
- (void)adjustedContentInsetDidChange API_AVAILABLE(ios(11.0),tvos(11.0)) NS_REQUIRES_SUPER;

@property(nonatomic) UIScrollViewContentInsetAdjustmentBehavior contentInsetAdjustmentBehavior API_AVAILABLE(ios(11.0),tvos(11.0));


@property(nonatomic,readonly,strong) UILayoutGuide *contentLayoutGuide API_AVAILABLE(ios(11.0),tvos(11.0));


@property(nonatomic,readonly,strong) UILayoutGuide *frameLayoutGuide API_AVAILABLE(ios(11.0),tvos(11.0));

四、 约束

1、NSLayoutConstraint

@interface UIView (UIConstraintBasedLayoutInstallingConstraints)

@property(nonatomic,readonly) NSArray<__kindof NSLayoutConstraint *> *constraints NS_AVAILABLE_IOS(6_0);

- (void)addConstraint:(NSLayoutConstraint *)constraint NS_AVAILABLE_IOS(6_0); // This method will be deprecated in a future release and should be avoided.  Instead, set NSLayoutConstraint's active property to YES.
- (void)addConstraints:(NSArray<__kindof NSLayoutConstraint *> *)constraints NS_AVAILABLE_IOS(6_0); // This method will be deprecated in a future release and should be avoided.  Instead use +[NSLayoutConstraint activateConstraints:].
- (void)removeConstraint:(NSLayoutConstraint *)constraint NS_AVAILABLE_IOS(6_0); // This method will be deprecated in a future release and should be avoided.  Instead set NSLayoutConstraint's active property to NO.
- (void)removeConstraints:(NSArray<__kindof NSLayoutConstraint *> *)constraints NS_AVAILABLE_IOS(6_0); // This method will be deprecated in a future release and should be avoided.  Instead use +[NSLayoutConstraint deactivateConstraints:].
@end





NS_CLASS_AVAILABLE_IOS(6_0)
@interface NSLayoutConstraint : NSObject


// 创建约束
+ (NSArray<__kindof NSLayoutConstraint *> *)constraintsWithVisualFormat:(NSString *)format options:(NSLayoutFormatOptions)opts metrics:(nullable NSDictionary<NSString *,id> *)metrics views:(NSDictionary<NSString *, id> *)views;



// 创建约束
+(instancetype)constraintWithItem:(id)view1 attribute:(NSLayoutAttribute)attr1 relatedBy:(NSLayoutRelation)relation toItem:(nullable id)view2 attribute:(NSLayoutAttribute)attr2 multiplier:(CGFloat)multiplier constant:(CGFloat)c;






// 使约束有效，类方法

+ (void)activateConstraints:(NSArray<NSLayoutConstraint *> *)constraints NS_AVAILABLE(10_10, 8_0);

// 使约束无效，类方法
+ (void)deactivateConstraints:(NSArray<NSLayoutConstraint *> *)constraints NS_AVAILABLE(10_10, 8_0);


// 返回NSLayoutAnchor

@property (readonly, copy) NSLayoutAnchor *firstAnchor NS_AVAILABLE(10_12, 10_0);
@property (readonly, copy, nullable) NSLayoutAnchor *secondAnchor NS_AVAILABLE(10_12, 10_0);

2、NSLayoutAnchor

iOS 9 可以用

例子： [[self.redView.topAnchor constraintEqualToAnchor:self.yellowView.topAnchor] setActive:true];

NS_CLASS_AVAILABLE_IOS(9_0)
@interface NSLayoutAnchor<AnchorType> : NSObject

NS_CLASS_AVAILABLE_IOS(9_0)
@interface NSLayoutXAxisAnchor : NSLayoutAnchor<NSLayoutXAxisAnchor *>

NS_CLASS_AVAILABLE_IOS(9_0)
@interface NSLayoutYAxisAnchor : NSLayoutAnchor<NSLayoutYAxisAnchor *>


NS_CLASS_AVAILABLE_IOS(9_0)
@interface NSLayoutDimension : NSLayoutAnchor<NSLayoutDimension *>


@interface UIView (UIViewLayoutConstraintCreation)
/* Constraint creation conveniences. See NSLayoutAnchor.h for details.
 */
@property(nonatomic,readonly,strong) NSLayoutXAxisAnchor *leadingAnchor NS_AVAILABLE_IOS(9_0);
@property(nonatomic,readonly,strong) NSLayoutXAxisAnchor *trailingAnchor NS_AVAILABLE_IOS(9_0);
@property(nonatomic,readonly,strong) NSLayoutXAxisAnchor *leftAnchor NS_AVAILABLE_IOS(9_0);
@property(nonatomic,readonly,strong) NSLayoutXAxisAnchor *rightAnchor NS_AVAILABLE_IOS(9_0);
@property(nonatomic,readonly,strong) NSLayoutYAxisAnchor *topAnchor NS_AVAILABLE_IOS(9_0);
@property(nonatomic,readonly,strong) NSLayoutYAxisAnchor *bottomAnchor NS_AVAILABLE_IOS(9_0);
@property(nonatomic,readonly,strong) NSLayoutDimension *widthAnchor NS_AVAILABLE_IOS(9_0);//尺寸
@property(nonatomic,readonly,strong) NSLayoutDimension *heightAnchor NS_AVAILABLE_IOS(9_0);
@property(nonatomic,readonly,strong) NSLayoutXAxisAnchor *centerXAnchor NS_AVAILABLE_IOS(9_0);
@property(nonatomic,readonly,strong) NSLayoutYAxisAnchor *centerYAnchor NS_AVAILABLE_IOS(9_0);
@property(nonatomic,readonly,strong) NSLayoutYAxisAnchor *firstBaselineAnchor NS_AVAILABLE_IOS(9_0);
@property(nonatomic,readonly,strong) NSLayoutYAxisAnchor *lastBaselineAnchor NS_AVAILABLE_IOS(9_0);

@end



@interface UIView (UILayoutGuideSupport)
@property(nonatomic,readonly,copy) NSArray<__kindof UILayoutGuide *> *layoutGuides NS_AVAILABLE_IOS(9_0);
- (void)addLayoutGuide:(UILayoutGuide *)layoutGuide NS_AVAILABLE_IOS(9_0);
- (void)removeLayoutGuide:(UILayoutGuide *)layoutGuide NS_AVAILABLE_IOS(9_0);
@end



@interface UILayoutGuide : NSObject <NSCoding>

@property(nonatomic,readonly) CGRect layoutFrame;


@property(nonatomic,weak,nullable) UIView *owningView;

@property(nonatomic,copy) NSString *identifier;


@property(nonatomic,readonly,strong) NSLayoutXAxisAnchor *leadingAnchor;
@property(nonatomic,readonly,strong) NSLayoutXAxisAnchor *trailingAnchor;
@property(nonatomic,readonly,strong) NSLayoutXAxisAnchor *leftAnchor;
@property(nonatomic,readonly,strong) NSLayoutXAxisAnchor *rightAnchor;
@property(nonatomic,readonly,strong) NSLayoutYAxisAnchor *topAnchor;
@property(nonatomic,readonly,strong) NSLayoutYAxisAnchor *bottomAnchor;
@property(nonatomic,readonly,strong) NSLayoutDimension *widthAnchor;
@property(nonatomic,readonly,strong) NSLayoutDimension *heightAnchor;
@property(nonatomic,readonly,strong) NSLayoutXAxisAnchor *centerXAnchor;
@property(nonatomic,readonly,strong) NSLayoutYAxisAnchor *centerYAnchor;

@end








@interface UIView (UIConstraintBasedCompatibility) 

/* By default, the autoresizing mask on a view gives rise to constraints that fully determine 
 the view's position. This allows the auto layout system to track the frames of views whose 
 layout is controlled manually (through -setFrame:, for example).
 When you elect to position the view using auto layout by adding your own constraints, 
 you must set this property to NO. IB will do this for you.
 */
@property(nonatomic) BOOL translatesAutoresizingMaskIntoConstraints NS_AVAILABLE_IOS(6_0); // Default YES

/* constraint-based layout engages lazily when someone tries to use it (e.g., adds a constraint to a view).  If you do all of your constraint set up in -updateConstraints, you might never even receive updateConstraints if no one makes a constraint.  To fix this chicken and egg problem, override this method to return YES if your view needs the window to use constraint-based layout.  
 */
#if UIKIT_DEFINE_AS_PROPERTIES
@property(class, nonatomic, readonly) BOOL requiresConstraintBasedLayout NS_AVAILABLE_IOS(6_0);
#else
+ (BOOL)requiresConstraintBasedLayout NS_AVAILABLE_IOS(6_0);
#endif

@end

总结如下， 系统提供的三种约束布局方法

1，创建约束VFL格式， 然后对View进行addConstraint增加约束。

+ (NSArray<__kindof NSLayoutConstraint *> *)constraintsWithVisualFormat:(NSString *)format options:(NSLayoutFormatOptions)opts metrics:(nullable NSDictionary<NSString *,id> *)metrics views:(NSDictionary<NSString *, id> *)views;

2，创建约束指定y = a*x+b公式，对View进行addConstraint增加约束。

+(instancetype)constraintWithItem:(id)view1 attribute:(NSLayoutAttribute)attr1 relatedBy:(NSLayoutRelation)relation toItem:(nullable id)view2 attribute:(NSLayoutAttribute)attr2 multiplier:(CGFloat)multiplier constant:(CGFloat)c;

3, 使用NSLayoutAnchor工厂，返回约束，在设置Active
iOS 9可用。 需要使用到
NSLayoutAnchor、NSLayoutXAxisAnchor、NSLayoutYAxisAnchor、NSLayoutDimension

NSLayoutConstraint提供的方法：
@property (getter=isActive) BOOL active NS_AVAILABLE(10_10, 8_0);
+ (void)activateConstraints:(NSArray<NSLayoutConstraint *> *)constraints NS_AVAILABLE(10_10, 8_0);
+ (void)deactivateConstraints:(NSArray<NSLayoutConstraint *> *)constraints NS_AVAILABLE(10_10, 8_0);

举例：

    // you must set this property to NO. IB will do this for you.
    NSLog(@"translatesAutoresizingMaskIntoConstraints在使用约束布局，必须设置为NO, 因为我们是从xib拖拽的View，xib会自动加这个特性值为:   %@",  self.redView.translatesAutoresizingMaskIntoConstraints ? @"YES" :@"NO");
    self.redView.translatesAutoresizingMaskIntoConstraints = NO;
    // 试图激活一个没有共同祖先的约束，将导致抛出一个异常
    
    
    if (@available(iOS 11.0, *)) {
        [NSLayoutConstraint
         activateConstraints:
         @[
           [self.redView.topAnchor constraintEqualToAnchor:self.view.safeAreaLayoutGuide.topAnchor constant:20],
           [self.redView.leftAnchor constraintEqualToAnchor:self.view.safeAreaLayoutGuide.leftAnchor constant:20],
           [self.redView.heightAnchor constraintEqualToConstant:50],
           [self.redView.widthAnchor constraintEqualToConstant:200]
           ]
         ];
    } else {
        // Fallback on earlier versions
    }
    

UIViewContorller Show The File Inspector 设置
Use Safe Area Layout Guides 开关

UITopLayout Guide ----- UIViewContorller topLayoutGuide \bottomLayoutGuide
UIBottomLayout Guide

UIView属性的insetsLayoutMarginsFromSafeArea --- XIB 与UIView的 Show the Sizes Inspector的Safe Area Relative Margins 相对应

Relative to margin 相对于边缘 开关
Respect language direction 遵照语言方向 开关

edge inset
边缘、插页、插入物

margins
页边、边缘

storyboard拆分， ios9以上才可以用。

Storyboard References cannot be the destinations of relationship segues prior to iOS 9.0