Storing and retrieving a custom object from NSPasteBoard - macos

Question

I have an object that belongs to this class that contains the following declarations:
HEADER
#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 holds other objects of this class, node holds objects that can be NSView or NSImageView.
I would like to be able to copy and paste objects of this type to/from NSPasteboard.
I have google around but the explanations are vague.
What should I do to make this class copiable/readable to NSPasteboard or in other words, make it conform to NSPasteboardWriting and NSPasteboardReading protocols?
I don't have the slightest clue on how this is done and as usual, Apple documetation and nothing is the same thing.

Answer 1

This is the complete solution.
First thing is to make the class conforming to NSCoding too. In that case the class declaration will be
#interface MyClassObject : NSObject <NSCopying, NSPasteboardWriting, NSPasteboardReading, NSCoding>
To make it compatible with NSCoding you have to implement encodeWithCoder: and initWithCoder:... in my case:
- (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
}
To make the class work with NSPasteboard you have to add these 4 methods:
-(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];
}
Then, on the class you implement the copy and paste you add:
- (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.
}
}

Answer 2

Ill only discuss writing. it is basically the same for reading (but in reverse of course ;))
write
declare the type you write
- (NSArray *)writableTypesForPasteboard:(NSPasteboard *)pasteboard {
return #[#"com.mycompany.mytype"];
}
write the data
- (id)pasteboardPropertyListForType:(NSString *)type {
//check the type we are asked to write
if(![type isEqualToString:#"com.mycompany.mytype"]) return nil;
//create a _plist_ object
// :: ONLY PLIST TYPES
NSMutableDictionary *plist = [[NSMutableDictionary alloc] init];
...
return plist;
}