1、Drag and Drop简介

　　Drag and Drop是iOS11的新特性，可以将文本、图片进行拖拽到不同app中，实现数据的传递。只不过只能在iPad上使用，iPhone上只能app内部拖拽！

 

2、简单使用

　　相关代码：

#import "ViewController.h"#define CScreenWidth        [[UIScreen mainScreen] bounds].size.width#define CScreenHeight       [[UIScreen mainScreen] bounds].size.height#define ScreenHeight        self.view.frame.size.height#define ScreenWidth         self.view.frame.size.width@interface ViewController ()
      
       @property (nonatomic, strong)UIImageView *img;@property (nonatomic, strong)UIImageView *img2;@end@implementation ViewController- (void)viewDidLoad {    [super viewDidLoad];    self.img =[[UIImageView alloc] initWithImage:[UIImage imageNamed:@"pic4"]];    self.img.frame = CGRectMake(20, 40, CScreenWidth-40, 200);    self.img.userInteractionEnabled = YES;    [self.view addSubview:self.img];    //Drag发送数据，Drop接收数据    UIDragInteraction *dragInter = [[UIDragInteraction alloc] initWithDelegate:self];    dragInter.enabled = YES;    [self.img addInteraction:dragInter];    [self.view addInteraction:[[UIDropInteraction alloc] initWithDelegate:self]];        self.img2 =[[UIImageView alloc] init];    self.img2.frame = CGRectMake(20, CScreenHeight-250, CScreenWidth-40, 200);    self.img2.userInteractionEnabled = YES;    [self.view addSubview:self.img2];    }#pragma mark -UIDragInteractionDelegate//提供数据源  开始拖拽- (NSArray
       
         *)dragInteraction:(UIDragInteraction *)interaction itemsForBeginningSession:(id
        
         )session{    NSLog(@"11111----");    self.img2.image = nil;    NSItemProvider *item = [[NSItemProvider alloc] initWithObject:self.img.image];    UIDragItem *dragItem = [[UIDragItem alloc] initWithItemProvider:item];    dragItem.localObject = self.img.image;    return @[dragItem];}//提供preview相关信息- (nullable UITargetedDragPreview *)dragInteraction:(UIDragInteraction *)interaction previewForLiftingItem:(UIDragItem *)item session:(id
         
          )session{    NSLog(@"22222----");    UIDragPreviewParameters *parameters = [[UIDragPreviewParameters alloc] init];    //设置蒙版mask    parameters.visiblePath = [UIBezierPath bezierPathWithRoundedRect:self.img.bounds cornerRadius:20];    //设置在哪个父视图和哪个位置展示    UIDragPreviewTarget *target = [[UIDragPreviewTarget alloc] initWithContainer:self.img.superview center:self.img.center];    UITargetedDragPreview *dragePreview = [[UITargetedDragPreview alloc] initWithView:interaction.view parameters:parameters target:target];    return dragePreview;}//drag进行时- (void)dragInteraction:(UIDragInteraction *)interaction willAnimateLiftWithAnimator:(id
          
           )animator session:(id
           
            )session{ NSLog(@"33333----"); [animator addCompletion:^(UIViewAnimatingPosition finalPosition) { if (finalPosition == UIViewAnimatingPositionEnd) { self.img.alpha = 0.5; } }];}//drag将要结束时调用- (void)dragInteraction:(UIDragInteraction *)interaction session:(id
            
             )session willEndWithOperation:(UIDropOperation)operation{ NSLog(@"44444----"); [UIView animateWithDuration:0.5 animations:^{ self.img.alpha = 1; }];}//drag动画将要取消时- (void)dragInteraction:(UIDragInteraction *)interaction item:(UIDragItem *)item willAnimateCancelWithAnimator:(id
             
              )animator{ NSLog(@"55555----"); [animator addAnimations:^{ self.img.alpha = .1; }];}//drag已经结束时调用- (void)dragInteraction:(UIDragInteraction *)interaction session:(id
              
               )session didEndWithOperation:(UIDropOperation)operation{ NSLog(@"66666----"); [UIView animateWithDuration:0.5 animations:^{ self.img.alpha = 1; }];}#pragma mark --UIDropInteractionDelegate//是否可以接收来自Drag数据- (BOOL)dropInteraction:(UIDropInteraction *)interaction canHandleSession:(id
               
                )session{ if(session.localDragSession == nil){ //说明数据来自外界 } return [session canLoadObjectsOfClass:[UIImage class]];}//第二次判断是否可以接收 无法接收用UIDropOperationCancel- (UIDropProposal *)dropInteraction:(UIDropInteraction *)interaction sessionDidUpdate:(id
                
                 )session{ UIDropOperation opera = session.localDragSession? UIDropOperationCopy:UIDropOperationCancel; return [[UIDropProposal alloc] initWithDropOperation:opera];}//取出来自drag的数据- (void)dropInteraction:(UIDropInteraction *)interaction performDrop:(id
                 
                  )session{ if (session.localDragSession) { NSProgress *pregesss = [session loadObjectsOfClass:[UIImage class] completion:^(NSArray<__kindof id
                  
                   > * _Nonnull objects) { // 回调的代码块默认就在主线程 for (id objc in objects) { UIImage *image = (UIImage *)objc; if (image) { self.img2.image = image; } } }]; }}@end
                  
                 
                
               
              
             
            
           
          
         
        
       
      

 

3、有关方法简介

　　UIDragInteraction和Delegate方法：

@protocol UIDragInteractionDelegate, UIDragSession;@class UIDragItem, UITargetedDragPreview;API_AVAILABLE(ios(11.0)) API_UNAVAILABLE(watchos, tvos) @protocol UIDragAnimating 
     
      - (void)addAnimations:(void (^)(void))animations;- (void)addCompletion:(void (^)(UIViewAnimatingPosition finalPosition))completion;@endUIKIT_EXTERN API_AVAILABLE(ios(11.0)) API_UNAVAILABLE(watchos, tvos) @interface UIDragInteraction : NSObject 
      
       - (instancetype)initWithDelegate:(id
       
        )delegate NS_DESIGNATED_INITIALIZER;- (instancetype)init NS_UNAVAILABLE;+ (instancetype)new NS_UNAVAILABLE;@property (nonatomic, nullable, readonly, weak) id
        
          delegate;@property (nonatomic) BOOL allowsSimultaneousRecognitionDuringLift;@property (nonatomic, getter=isEnabled) BOOL enabled;@property (class, nonatomic, readonly, getter=isEnabledByDefault) BOOL enabledByDefault;@endAPI_AVAILABLE(ios(11.0)) API_UNAVAILABLE(watchos, tvos) @protocol UIDragInteractionDelegate 
         
          @required//提供数据源  长按UI开始拖拽- (NSArray
          
            *)dragInteraction:(UIDragInteraction *)interaction itemsForBeginningSession:(id
           
            )session;@optional//提供UITargetedDragPreview的相关信息 长按UI是有个lift（UI举起效果，系统自动生成）//返回nil 没有效果； 不实现该方法 interaction.view自动生成UITargetedDragPreview- (nullable UITargetedDragPreview *)dragInteraction:(UIDragInteraction *)interaction previewForLiftingItem:(UIDragItem *)item session:(id
            
             )session;//drag发生时调用- (void)dragInteraction:(UIDragInteraction *)interaction willAnimateLiftWithAnimator:(id
             
              )animator session:(id
              
               )session;//将要开始drag- (void)dragInteraction:(UIDragInteraction *)interaction sessionWillBegin:(id
               
                )session;//是否允许数据移动 app内移动有效，跨app总是复制数据- (BOOL)dragInteraction:(UIDragInteraction *)interaction sessionAllowsMoveOperation:(id
                
                 )session;//是否允许跨应用程序进行drag ipad- (BOOL)dragInteraction:(UIDragInteraction *)interaction sessionIsRestrictedToDraggingApplication:(id
                 
                  )session;//设置预览视图是否显示原始大小- (BOOL)dragInteraction:(UIDragInteraction *)interaction prefersFullSizePreviewsForSession:(id
                  
                   )session;//已经结束移动- (void)dragInteraction:(UIDragInteraction *)interaction sessionDidMove:(id
                   
                    )session;//drag将要结束时调用- (void)dragInteraction:(UIDragInteraction *)interaction session:(id
                    
                     )session willEndWithOperation:(UIDropOperation)operation;//drag已经结束时调用- (void)dragInteraction:(UIDragInteraction *)interaction session:(id
                     
                      )session didEndWithOperation:(UIDropOperation)operation;//拖拽源进行了放置操作后调用- (void)dragInteraction:(UIDragInteraction *)interaction sessionDidTransferItems:(id
                      
                       )session;//设置是否允许向拖拽中的项目添加数据 返回数据载体数组 drag时点击拖拽的组件调用- (NSArray
                       
                         *)dragInteraction:(UIDragInteraction *)interaction itemsForAddingToSession:(id
                        
                         )session withTouchAtPoint:(CGPoint)point;//设置允许进行拖拽中追加数据的拖拽行为会话- (nullable id
                         
                          )dragInteraction:(UIDragInteraction *)interaction sessionForAddingItems:(NSArray
                          
                           
                            > *)sessions withTouchAtPoint:(CGPoint)point;//将要向拖拽组件中追加数据时调用- (void)dragInteraction:(UIDragInteraction *)interaction session:(id
                            
                             )session willAddItems:(NSArray
                             
                               *)items forInteraction:(UIDragInteraction *)addingInteraction;//设置拖拽动作取消的视图动画 返回nil则消除动画- (nullable UITargetedDragPreview *)dragInteraction:(UIDragInteraction *)interaction previewForCancellingItem:(UIDragItem *)item withDefault:(UITargetedDragPreview *)defaultPreview;//drag动画将要取消时调用- (void)dragInteraction:(UIDragInteraction *)interaction item:(UIDragItem *)item willAnimateCancelWithAnimator:(id
                              
                               )animator;
                              
                             
                            
                           
                          
                         
                        
                       
                      
                     
                    
                   
                  
                 
                
               
              
             
            
           
          
         
        
       
      
     

　　UIDropInteraction和Delegate方法：

@protocol UIDragAnimating, UIDropInteractionDelegate, UIDropSession;@class UIDragItem, UITargetedDragPreview;UIKIT_EXTERN API_AVAILABLE(ios(11.0)) API_UNAVAILABLE(watchos, tvos) @interface UIDropInteraction : NSObject 
     
      - (instancetype)initWithDelegate:(id
      
       )delegate NS_DESIGNATED_INITIALIZER;- (instancetype)init NS_UNAVAILABLE;+ (instancetype)new NS_UNAVAILABLE;@property (nonatomic, nullable, readonly, weak) id
       
         delegate;@property (nonatomic, assign) BOOL allowsSimultaneousDropSessions;@endtypedef NS_ENUM(NSUInteger, UIDropOperation) {    UIDropOperationCancel   = 0,    UIDropOperationForbidden = 1,    UIDropOperationCopy      = 2,    UIDropOperationMove      = 3,} API_AVAILABLE(ios(11.0)) API_UNAVAILABLE(watchos, tvos);UIKIT_EXTERN API_AVAILABLE(ios(11.0)) API_UNAVAILABLE(watchos, tvos) @interface UIDropProposal : NSObject 
        
         - (instancetype)initWithDropOperation:(UIDropOperation)operation NS_DESIGNATED_INITIALIZER;- (instancetype)init NS_UNAVAILABLE;+ (instancetype)new NS_UNAVAILABLE;@property (nonatomic, readonly) UIDropOperation operation;@property (nonatomic, getter=isPrecise) BOOL precise;@property (nonatomic) BOOL prefersFullSizePreview;@endAPI_AVAILABLE(ios(11.0)) API_UNAVAILABLE(watchos, tvos) @protocol UIDropInteractionDelegate 
         
          @optional//是否可以处理来自Drag的数据- (BOOL)dropInteraction:(UIDropInteraction *)interaction canHandleSession:(id
          
           )session;//Drag的UI元素进入Drop的区域- (void)dropInteraction:(UIDropInteraction *)interaction sessionDidEnter:(id
           
            )session;//第二次判断是否可以接收 无法接收用UIDropOperationCancel- (UIDropProposal *)dropInteraction:(UIDropInteraction *)interaction sessionDidUpdate:(id
            
             )session;//Drag的UI元素离开Drop的区域- (void)dropInteraction:(UIDropInteraction *)interaction sessionDidExit:(id
             
              )session;//取出来自drag的数据
             
            
           
          
         
        
       
      
     

NSLog(@"%f,%f",[session locationInView:self.view].x,[session locationInView:self.view].y)

- (void)dropInteraction:(UIDropInteraction *)interaction performDrop:(id
     
      )session;//drop结束- (void)dropInteraction:(UIDropInteraction *)interaction concludeDrop:(id
      
       )session;//整个Drag和Drop结束- (void)dropInteraction:(UIDropInteraction *)interaction sessionDidEnd:(id
       
        )session;//手指松开，控制Drag Preview 如何自然的过渡到Drop之后的Preview- (nullable UITargetedDragPreview *)dropInteraction:(UIDropInteraction *)interaction previewForDroppingItem:(UIDragItem *)item withDefault:(UITargetedDragPreview *)defaultPreview;//手指松开Drop时，控制Drop区域的其他UI元素如何展示动画- (void)dropInteraction:(UIDropInteraction *)interaction item:(UIDragItem *)item willAnimateDropWithAnimator:(id
        
         )animator;@end