macos - 从 NSPasteBoard 存储和检索自定义对象

Question

我有一个属于此类的对象，其中包含以下声明:

标题

@interface MyClassObject : NSObject <NSCopying, NSPasteboardWriting, NSPasteboardReading>

@property (nonatomic, strong) NSArray *children;
@property (nonatomic, assign) NSInteger type;
@property (nonatomic, strong) NSString *name;
@property (nonatomic, strong) id node;

children 保存此类的其他对象，node 保存可以是 NSView 或 NSImageView 的对象。

我希望能够将这种类型的对象复制到 NSPasteboard 或从 NSPasteboard 粘贴。

我用谷歌搜索过，但解释很模糊。

我应该怎样做才能使此类可复制/可读到 NSPasteboard，或者换句话说，使其符合 NSPasteboardWriting 和 NSPasteboardReading 协议(protocol)？

我对这是如何完成的一无所知，并且像往常一样，Apple 文档并没有什么是相同的。

Answer 1

这是完整的解决方案。

首先要做的就是使类也符合 NSCoding 。在这种情况下，类声明将是

@interface MyClassObject : NSObject <NSCopying, NSPasteboardWriting, NSPasteboardReading, NSCoding>

为了使其与 NSCoding 兼容，您必须实现 encodeWithCoder: 和 initWithCoder:... 在我的例子中:

- (void)encodeWithCoder:(NSCoder *)coder {

  [coder encodeObject:@(self.type) forKey:@"type"];
  [coder encodeObject:self.name forKey:@"name"];
  // converting the node to NSData... 
  // the object contained in node must be compatible with NSCoding
  NSData *nodeData = [NSKeyedArchiver archivedDataWithRootObject:self.node];
  [coder encodeObject:nodeData forKey:@"node"];

  NSData *childrenData = [NSKeyedArchiver archivedDataWithRootObject:self.children];
  [coder encodeObject:childrenData forKey:@"children"];

}

- (id)initWithCoder:(NSCoder *)coder {

  self = [super init];

  if (self) {

    _type = [[coder decodeObjectForKey:@"type"] integerValue];
    _name = [coder decodeObjectForKey:@"name"];

    NSData *nodeData = [coder decodeObjectForKey:@"node"];
    _efeito = [NSKeyedUnarchiver unarchiveObjectWithData:nodeData];

    NSData *childrenData = [coder decodeObjectForKey:@"children"];
    _children = [NSKeyedUnarchiver unarchiveObjectWithData:childrenData];
    _parent = nil;  // I want this to be nil when the object is recreated
  }

要使该类与 NSPasteboard 一起使用，您必须添加以下 4 个方法:

-(id)initWithPasteboardPropertyList:(id)propertyList ofType:(NSString *)type {
  return [NSKeyedUnarchiver unarchiveObjectWithData:propertyList];
}


+(NSArray *)readableTypesForPasteboard:(NSPasteboard *)pasteboard {
    // I am using the bundleID as a type  
    return @[[[NSBundle mainBundle] bundleIdentifier]];
}

- (NSArray *)writableTypesForPasteboard:(NSPasteboard *)pasteboard {
  // I am using the bundleID as a type  
  return @[[[NSBundle mainBundle] bundleIdentifier]];
}


- (id)pasteboardPropertyListForType:(NSString *)type {
  // I am using the bundleID as a type  
  if(![type isEqualToString:[[NSBundle mainBundle] bundleIdentifier]]) {
    return nil;
  }

  return [NSKeyedArchiver archivedDataWithRootObject:self];
}

然后，在您实现添加的复制和粘贴的类上:

- (void)copy:(id)sender {

  NSPasteboard *pasteBoard = [NSPasteboard generalPasteboard];
  [pasteBoard clearContents];

  NSArray *copiedObjects = @[theObjectYouWantToCopyToThePasteboard];
  [pasteBoard writeObjects:copiedObjects];

}

- (void)paste:sender {

  NSPasteboard *pasteboard = [NSPasteboard generalPasteboard];
  NSArray *classArray = @[[LayerObject class]];
  NSDictionary *options = [NSDictionary dictionary];

  BOOL ok = [pasteboard canReadItemWithDataConformingToTypes:@[[[NSBundle mainBundle] bundleIdentifier]]];

  if (ok) {
    NSArray *objectsToPaste = [pasteboard readObjectsForClasses:classArray options:options];
    MyObjectClass *object = [objectsToPaste objectAtIndex:0];

    // object is the one you have copied to the pasteboard
    // now you can do whatever you want with it.
    // add the code here.    
  }
}