I have a custom class that I want to be able to put on the pasteboard.
Here is the code I have so far
- (NSArray *)writableTypesForPasteboard:(NSPasteboard *)pasteboard {
static NSArray *writableTypes = nil;
if (!writableTypes) {
writableTypes=[NSArray arrayWithObjects:(NSString *)kUTTypeXML, nil];
}
return writableTypes;
}
- (id)pasteboardPropertyListForType:(NSString *)type {
return [NSKeyedArchiver archivedDataWithRootObject:[MyClass class]];
}
This part isn't right:
- (id)pasteboardPropertyListForType:(NSString *)type {
return [NSKeyedArchiver archivedDataWithRootObject:[MyClass class]];
}
It looks like you're trying to archive the actual MyClass class, where you should actually be archiving the MyClass object, i.e. a specific instance of MyClass rather than the class itself. Also, you should probably be checking the type that's passed in to make sure that you're offering the data for the right thing. So, it should look something like:
- (id)pasteboardPropertyListForType:(NSString *)type {
if ([type isEqualToString:kUTTypeXML]) {
return [NSKeyedArchiver archivedDataWithRootObject:self.someInstanceOfMyClass];
}
return nil;
}
Finally, make sure that MyClass implements the NSCoding protocol so that you can create an archive containing the object's data.
Related
I use lazy instantiation on my properties, to have my class created and used as fast as possible. To achieve this, I write lots of 'empty' getters like this:
- (VMPlacesListFilter *)currentFilter
{
if (!_currentFilter) {
_currentFilter = [[VMPlacesListFilter alloc] init];
}
return _currentFilter;
}
They are all the same: if the instance variable is nil, call the -alloc and -init on the class of the property, then return the instance variable. Very common and straightforward.
If I don't create this getter by myself, Objective-C's automatic synthesization creates a getter for me, which does only the returning part (does not init the object if the instance variable is nil).
Is there any way to avoid writing this boilerplate code?
Nope, I'm afraid there's no good way around it, if you really want to have lazy initialization. Personally, I usually save lazy initialization for stuff that could really be time consuming or memory intensive (say, loading images or view controllers), and initialize cheap stuff (like simple data structures or model objects) in init.
- (instancetype) init {
self = [super init];
if( self ) {
_cheapThing1 = [NSMutableArray array];
_cheapThing2 = [[MyModelObject alloc] init];
}
return self;
}
- (ExpensiveThing*) expensiveThing
{
if( _expensiveThing == nil ) {
_expensiveThing = [[ExpensiveThing alloc] init];
}
return _expensiveThing;
}
Unless you're loading something from disk or the network, I wouldn't worry too much about initialization time. Of course, profile it.
I know this is an Objective-C question, but it's worth noting that Swift has lazy initialization built-in.
lazy var currentFilter = VMPlacesListFilter()
First off, I totally agree with #zpasternack that "lazy load" should not be misused. However, automatically generating setters and getters is completely doable with the power of Objective-C runtime. In fact, CoreData is doing this.
Anyway, I have come up with some stupid code implementing a class called LazyClass, in which you can declare dynamic properties like lazyArray (see below). Using dynamic method resolution, when the property is accessed for the first time, a getter that calls the corresponding class's default +alloc and -init method will be automatically added to the class. All underlying instance variables are stored in an NSMutableDictionary called myVars. Of course you can manipulate ivars through the runtime API as well, but using a dictionary should save some work.
Please note that this implementation just shows the basic idea of how it works. It lacks error checking and is not supposed to be shipped.
LazyClass.h
#interface LazyClass : NSObject
#property NSMutableDictionary *myVars;
// lazily initialized property
#property NSArray *lazyArray;
#end
LazyClass.m
#import "LazyClass.h"
#import <objc/objc-runtime.h>
#implementation LazyClass
#dynamic lazyArray;
- (instancetype)init {
self = [super init];
self.myVars = [NSMutableDictionary dictionary];
return self;
}
- (NSMutableDictionary *)getMyVars {
return self.myVars;
}
// the generated getter method
id dynamicGetterMethodIMP(id self, SEL _cmd) {
// selector name, which is also the property name
const char *selName = sel_getName(_cmd);
NSString *selNSName = [NSString stringWithCString:selName encoding:NSUTF8StringEncoding];
NSString *keyPath = [NSString stringWithFormat:#"myVars.%#", selNSName];
if (![self valueForKeyPath:keyPath]) {
// get the actual type of the property
objc_property_t property = class_getProperty([self class], selName);
const char *attr = property_getAttributes(property);
NSString *attrString = [[NSString alloc] initWithCString:attr encoding:NSUTF8StringEncoding];
NSString *typeAttr = [[attrString componentsSeparatedByString:#","] firstObject];
NSString *typeName = [typeAttr substringWithRange:NSMakeRange(3, typeAttr.length - 4)];
// the default initialization
Class typeClass = NSClassFromString(typeName);
[self setValue:[[typeClass alloc] init] forKeyPath:keyPath];
}
return [self valueForKeyPath:keyPath];
}
// the generated setter method
void dynamicSetterMethodIMP(id self, SEL _cmd, id value) {
// get the property name out of selector name
// e.g. setLazyArray: -> lazyArray
NSString *propertyName = NSStringFromSelector(_cmd);
propertyName = [propertyName stringByReplacingOccurrencesOfString:#"set" withString:#""];
propertyName = [propertyName stringByReplacingOccurrencesOfString:#":" withString:#""];
propertyName = [NSString stringWithFormat:#"%#%#", [propertyName substringToIndex:1].lowercaseString, [propertyName substringFromIndex:1]];
NSString *keyPath = [NSString stringWithFormat:#"myVars.%#", propertyName];
[self setValue:value forKeyPath:keyPath];
}
// dynamic method resolution
+ (BOOL)resolveInstanceMethod:(SEL)aSEL {
if ([NSStringFromSelector(aSEL) containsString:#"set"]) {
class_addMethod([self class], aSEL, (IMP)dynamicSetterMethodIMP, "^?");
} else {
class_addMethod([self class], aSEL, (IMP)dynamicGetterMethodIMP, "v#:");
}
return YES;
}
#end
Documentation
If it's the verboseness that bothers you, I suppose you could compress lazy initialisers that only need one-line initialization using the ternary operator:
- (VMPlacesListFilter *)currentFilter
{
return _currentFilter ? : (_currentFilter = [[VMPlacesListFilter alloc] init]);
}
DISCLAIMER: I don't do this, but it's interesting that it can be done
I have two classes, Class A and Class B. They can both call the same method in a controller. The method they call takes in a CGPoint. Is there any way I can determine which class the argument came from?
I have tried using the following:
if ([point isKindOfClass:[_territoryPaths class]])
{
NSMutableDictionary *territoryPaths = [_territoryPaths territoryPaths];
}
if ([piont class] == [_territoryPaths class])
{
NSMutableDictionary *territoryPaths = [_territoryPaths territoryPaths];
}
point is the CGPoint that the method takes in.
The best way to deal with this situation if you want to use this method in a class that is not ClassA or ClassB would be to modify your method so that it accepts a sender and do the isKindOfClass on the sender value.
For example:
- (void)someMethod:(id)sender withPoint:(CGPoint)point
{
if ([sender isKindOfClass:[ClassA class]])
{
// Do class A stuff
}
else if ([sender isKindOfClass:[ClassB class]])
{
// Do class B stuff
}
else
{
// Unknown class
}
}
I find it hard to write/read array of custom objects. In my my app, Contact class has a NSDictionary as property and this dictionary has array as objects for keys.
I serialize/deserialize my objects with NSCoder and NSKeyedArchiever and even tried NSPropertyList serialization. I always get errors when serializing as soon as it starts to serialize NSDictionary. Here is my code and I didn't really find a general answer regarding how to serialize custom objects with complex structure?
//Contact.m
//phoneNumbers is a NSDictionary
#pragma mark Encoding/Decoding
-(void)encodeWithCoder:(NSCoder *)aCoder
{
NSLog(#"Encoding");
[aCoder encodeObject:self.firstName forKey:#"firstName"];
NSLog(#"First name encoded");
[aCoder encodeObject:self.lastName forKey:#"lastName"];
NSLog(#"Last name encoded");
[aCoder encodeInt:self.age forKey:#"age"];
NSLog(#"Age encoded");
NSString *errorStr;
NSData *dataRep = [NSPropertyListSerialization dataFromPropertyList:self.phoneNumbers
format:NSPropertyListXMLFormat_v1_0
errorDescription:&errorStr];
NSLog(#"Data class %#", [dataRep class]);
if(!dataRep)
{
NSLog(#"Error encoding %#", errorStr);
}
[aCoder encodeObject:dataRep forKey:#"phones"];
NSLog(#"Encoding finished");
}
- (id) initWithCoder: (NSCoder *)coder
{
if (self = [super init])
{
[self setFirstName:[coder decodeObjectForKey:#"firstName"]];
[self setLastName:[coder decodeObjectForKey:#"lastName"]];
[self setAge:[coder decodeIntForKey:#"age"]];
NSString *errorStr;
NSData *data=[coder decodeObjectForKey:#"phones"];
NSDictionary *propertyList = [NSPropertyListSerialization propertyListFromData:data mutabilityOption:NSPropertyListImmutable format:NULL errorDescription:&errorStr];
if(!propertyList)
{
NSLog(#"Error %#", errorStr);
}
[self setPhoneNumbers:propertyList];
}
return self;
}
//Serializing/Deserializing an array of Contact objects:
#pragma mark Import/Export
//Export Contacts to file
-(void)exportContactsToFile
{
BOOL done=[NSKeyedArchiver archiveRootObject:self.contacts toFile:[PathUtility getFilePath:#"phonebook"]];
NSLog(#"Export done: %i", done);
}
//Import Contacts from file
-(void)importContactsFromFile
{
self.contacts = [NSKeyedUnarchiver unarchiveObjectWithFile:[PathUtility getFilePath:#"phonebook"]];
}
Is there a generic good way to serialize/deserialize objects in objective-c? thanks
The error I get is:
0objc_msgSend
1 CF_Retain
...
that's stack trace, but I get no other errors(
You shouldn't need to use NSPropertyListSerialization for self.phoneNumbers. NSDictionary adheres to the NSCoding protocol.
So, [aCoder encodeObject:self.phoneNumbers forKey:#"phones"]; should be sufficient.
As long as a class adheres to NSCoding (which nearly all Apple-provided class do), you can just use -encodeObject:forKey:, since that method will call that object's implementation of -encodeWithCoder:
I have a special class in my proprietary library that automatically reads the list of its properties and use the getter and setter to encode and decode the object. Sorry I can't share the code here but I can at least give you steps by steps how my class works:
First, the class must be implement NSCoding and NSCopying protocols.
Inside + (void)initialize, iterate thru the definitions of the properties of the class using class_copyPropertyList(), property_getName() and property_copyAttributeList(). Refer Objective-C Runtime Programming Guide for details on these functions.
For each property, run thru its attribute list and get the attribute with strncmp(attribute.name, "T", 1) == 0 (yup, it's a c-string in there). Use that attribute value to determine the type of the property. For example, "i" means int, "I" means unsigned int, if it starts with a "{" then it's a struct etc. Refer this page on the Type Encoding.
Store the property name-type pairs inside a NSDictionary. At the end of properties iteration, store this dictionary inside a static and global NSMutableDictionary using the class name as the key.
To support auto-encoding, implement - (void)encodeWithCoder:(NSCoder *)aCoder to iterate thru the property name-type pair, calling the property getter method (usually - (returnType)propertyName) and encode it inside the coder using appropriate encodeType: method (e.g. encodeInt:, encodeFloat:, encodeObject:, encodeCGPoint: etc).
To support auto-decoding, implement - (id)initWithCoder:(NSCoder *)aDecoder to iterate thru the property name-type pair, decode it from the decoder using appropriate decodeTypeForKey: method (e.g. decodeIntForKey:, decodeFloatForKey:, decodeObjectForKey:, decodeCGPointForKey: etc). and call the property setter method (usually - (void)setPropertyName:).
Implement an instance method that trigger the encoding (luckily I can share this method here ^__^):
NSMutableData *data = [NSMutableData data];
NSKeyedArchiver *arc = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data];
[arc encodeRootObject:self];
[arc finishEncoding];
[arc release];
return data;
Once you have the NSData you can anything with it such as calling writeToFile:atomically: or even [[NSUserDefaults standardUserDefaults] setObject:[self wrapInNSData] forKey:key].
Also, implement a class method that returns a new instance of the object loaded from the file:
NSKeyedUnarchiver *unarc = [[NSKeyedUnarchiver alloc] initForReadingWithData:[NSData dataWithContentsOfFile:dataFilePath]];
MyCoolFileDataStore *data = [unarc decodeObject];
[unarc release];
return data;
Finally, to make another object class supports this auto-encoding-decoding, the class needs to extend the special class.
Sorry, it's a bit long winded, but for my case, the extra trouble that I took to create this class really save a lot of time along the road. Struggle today, breeze through tomorrow ;)
I wonder whether Objective-C offers any support for generics?
For instance, consider a method:
-(void) sort: (NSMutableArray *) deck {
}
Is there any way for me to make it only deal with Deck of Cards?
Is something like this possible to enforce?
-(void) sort: (NSMutableArray <Card *>) deck {
}
Objective-C supports lightweight Generics since 2015, with the Xcode 7.
The Xcode 7 compiler will give you the compiler warning if there is a type mismatch.
For example, the following line will raise a compiler warning as the second object in the array causes type mismatch. The array allows only NSString objects.
NSArray <NSString *> *myArray = [#"str2", #1, #"str2"];
You can use the introspection tools offered by the objective-c runtime.
Basically, it means you can check if all objects in an array either are a kind of class (Class A or one subclass of it) or a member of class (class A), or if a objects conforms to a protocol or responds to a selector (a certain method is present).
-(void) sort: (NSMutableArray *) deck {
for(id obj in deck){
if(obj isKindOfClass:[A class]]){
//this is of right class
}
}
}
You could write a Category method on NSArray that checkouts this on every object.
BOOL allAreKindOfA = [array allObjectsAreKindOfClass:[A class]];
Normally you actually don't need this very often, as you know what you put inside a collection.
If you need to check the type or ability of an object in a Array, this might be an indicator, that your Architecture is broken
Another option could be a subclass of NSMutableArray that only accepts certain classes. But be aware of the subclassing notes for NSMutableArray and NSArray, as these are Class-Clusters and therefore not easy to subclass.
Note: In my other answer I created a NSMutableArray subclass, that uses a block to test, if a certain requirement is fulfilled. If you test against class-membership, this will do exactly what you want. Use the second block for error handling.
As of Xcode 7's release, Apple has added support for Objective-C generics.
NSArray <NSString *> *arrayOfStrings = #[#"a", #"b"];
NSDictionary <NSString *, NSDate *> *dictionaryOfDates = #{ #"a" : #1 };
Inspired by MonomorphicArray I came up with another idea:
Create a subclass on NSMutableArray, that takes two blocks:
AddBlock — a block that test, if one or more requirements are full filed and adds the object only, if its passes the test
FailBlock — a block, that defines what happens, if the test was not successful.
The AddBlock could test for a certain class membership like
^BOOL(id element) {
return [element isKindOfClass:[NSString class]];
}
and the FailBlock can raise an exception, fail silently or add the element, that failed the test, to another Array. If no failBlock is provided, a default block will raise an error.
The blocks will define, if an array acts like an generic array, or as a filter.
I will give an complete example for the second case.
VSBlockTestedObjectArray.h
#import <Foundation/Foundation.h>
typedef BOOL(^AddBlock)(id element);
typedef void(^FailBlock)(id element);
#interface VSBlockTestedObjectArray : NSMutableArray
#property (nonatomic, copy, readonly) AddBlock testBlock;
#property (nonatomic, copy, readonly) FailBlock failBlock;
-(id)initWithTestBlock:(AddBlock)testBlock FailBlock:(FailBlock)failBlock Capacity:(NSUInteger)capacity;
-(id)initWithTestBlock:(AddBlock)testBlock FailBlock:(FailBlock)failBlock;
-(id)initWithTestBlock:(AddBlock)testBlock;
#end
VSBlockTestedObjectArray.m
#import "VSBlockTestedObjectArray.h"
#interface VSBlockTestedObjectArray ()
#property (nonatomic, retain) NSMutableArray *realArray;
-(void)errorWhileInitializing:(SEL)selector;
#end
#implementation VSBlockTestedObjectArray
#synthesize testBlock = _testBlock;
#synthesize failBlock = _failBlock;
#synthesize realArray = _realArray;
-(id)initWithCapacity:(NSUInteger)capacity
{
if (self = [super init]) {
_realArray = [[NSMutableArray alloc] initWithCapacity:capacity];
}
return self;
}
-(id)initWithTestBlock:(AddBlock)testBlock
FailBlock:(FailBlock)failBlock
Capacity:(NSUInteger)capacity
{
self = [self initWithCapacity:capacity];
if (self) {
_testBlock = [testBlock copy];
_failBlock = [failBlock copy];
}
return self;
}
-(id)initWithTestBlock:(AddBlock)testBlock FailBlock:(FailBlock)failBlock
{
return [self initWithTestBlock:testBlock FailBlock:failBlock Capacity:0];
}
-(id)initWithTestBlock:(AddBlock)testBlock
{
return [self initWithTestBlock:testBlock FailBlock:^(id element) {
[NSException raise:#"NotSupportedElement" format:#"%# faild the test and can't be add to this VSBlockTestedObjectArray", element];
} Capacity:0];
}
- (void)dealloc {
[_failBlock release];
[_testBlock release];
self.realArray = nil;
[super dealloc];
}
- (void) insertObject:(id)anObject atIndex:(NSUInteger)index
{
if(self.testBlock(anObject))
[self.realArray insertObject:anObject atIndex:index];
else
self.failBlock(anObject);
}
- (void) removeObjectAtIndex:(NSUInteger)index
{
[self.realArray removeObjectAtIndex:index];
}
-(NSUInteger)count
{
return [self.realArray count];
}
- (id) objectAtIndex:(NSUInteger)index
{
return [self.realArray objectAtIndex:index];
}
-(void)errorWhileInitializing:(SEL)selector
{
[NSException raise:#"NotSupportedInstantiation" format:#"not supported %#", NSStringFromSelector(selector)];
}
- (id)initWithArray:(NSArray *)anArray { [self errorWhileInitializing:_cmd]; return nil;}
- (id)initWithArray:(NSArray *)array copyItems:(BOOL)flag { [self errorWhileInitializing:_cmd]; return nil;}
- (id)initWithContentsOfFile:(NSString *)aPath{ [self errorWhileInitializing:_cmd]; return nil;}
- (id)initWithContentsOfURL:(NSURL *)aURL{ [self errorWhileInitializing:_cmd]; return nil;}
- (id)initWithObjects:(id)firstObj, ... { [self errorWhileInitializing:_cmd]; return nil;}
- (id)initWithObjects:(const id *)objects count:(NSUInteger)count { [self errorWhileInitializing:_cmd]; return nil;}
#end
Use it like:
VSBlockTestedObjectArray *stringArray = [[VSBlockTestedObjectArray alloc] initWithTestBlock:^BOOL(id element) {
return [element isKindOfClass:[NSString class]];
} FailBlock:^(id element) {
NSLog(#"%# can't be added, didn't pass the test. It is not an object of class NSString", element);
}];
VSBlockTestedObjectArray *numberArray = [[VSBlockTestedObjectArray alloc] initWithTestBlock:^BOOL(id element) {
return [element isKindOfClass:[NSNumber class]];
} FailBlock:^(id element) {
NSLog(#"%# can't be added, didn't pass the test. It is not an object of class NSNumber", element);
}];
[stringArray addObject:#"test"];
[stringArray addObject:#"test1"];
[stringArray addObject:[NSNumber numberWithInt:9]];
[stringArray addObject:#"test2"];
[stringArray addObject:#"test3"];
[numberArray addObject:#"test"];
[numberArray addObject:#"test1"];
[numberArray addObject:[NSNumber numberWithInt:9]];
[numberArray addObject:#"test2"];
[numberArray addObject:#"test3"];
NSLog(#"%#", stringArray);
NSLog(#"%#", numberArray);
Note: This code is not fully tested. Probably some of the unimplemented method should be implemented for usage in real world programs.
Not directly, no. There a few ways to simulate it, but it requires a lot of wrapper code, boilerplate code, and runtime overhead. I just switch to Objective-C++ and use C++ templates when I want or need proper generics.
So if you wanted to introduce typesafety/checks to an NSArray, you could approach it using something like this:
template <typename T>
class t_typed_NSMutableArray {
public:
t_typed_NSMutableArray() : d_array([NSMutableArray new]) {}
~t_typed_NSMutableArray() { [d_array release]; }
/* ... */
T* operator[](const size_t& idx) {
T* const obj([this->d_array objectAtIndex:idx]);
assert([obj isKindOfClass:[T class]]);
return obj;
}
void addObject(T* const obj) {
assert([obj isKindOfClass:[T class]]);
[this->d_array addObject:obj];
}
private:
NSMutableArray * const d_array;
};
in use:
t_typed_NSMutableArray<Card> array([self cards]); // < note this exact constructor is not defined
Card * firstCard = array[0]; // << ok
NSString * string = array[0]; // << warning
then you also get type safety and overloading when passing the collection, so you could not pass t_typed_NSArray<Card> as an t_typed_NSArray<NSURL>.
There is an easy, effective way of doing this (I've been using it on projects for a couple of years now). Sadly, someone deleted the answer, and my attempts to get it re-instated were rejected. Here goes again:
You can re-implement a cut-down version of C++ templating within Obj-C because Obj-C encapsulates all of C (and C++ templates are C-macros with some improved compiler/debugger support):
This only needs to be done once, using a single header file. Someone has done it for you:
https://github.com/tomersh/Objective-C-Generics
You end up with 100% legal Obj-C code that looks like this:
NSArray<CustomClass> anArray= ...
CustomClass a = anArray[0]; // works perfectly, and Xcode autocomplete works too!
This all works fine in XCode, with autocomplete, etc.
I need to drag a reference to an NSManagedObject between two table views of my application. What's the preferred NSPasteboard type to store a reference to an NSManagedObject?
My current solution is to store the URIRepresentation of the object's NSManagedObjectID in a NSPasteboardTypeString. I suspect there's a more elegant solution out there.
There is no standard type for all model objects since your model objects and how they're handled are unique to your application. If there was one pasteboard type for all then there'd be no telling them apart. Your own custom object should have its own drag type.
Just use a string that makes sense (maybe a #define so you can find it with auto-complete in Xcode) like "MyObjectPboardType" that resolves to "com.yourcompany.yourapp.yourobjecttype".
Use NSPasteboard's -declareTypes:owner: to declare your new type, then use -setString:forType: or one of the other -set?:forType: methods to set the information for your object's type. In your case, the use of the object ID is a perfectly acceptable identifier. Just remember managed objects' object IDs change when they're new versus persisted.
If you are dragging within tables in the same application you might as well put in pasteboard the rowIndexes (indexPaths in case you are dragging from an outlineView) of the objects in the tableView (outlineView). This might as well spare you from some unneeded CoreData access if the dataSource of the tableViews are NSArrayController (NSTreeController for outlineView).
You can then easily retrieve the dragged objects when accepting the drop since the ‘info‘ object passed to both methods ‘tableView:validateDrop:proposedRow: proposedDropOperation:‘ and to ‘tableView:acceptDrop:row:dropOperation:‘ will have a reference to the tableView originating the drag under ‘draggingSource‘ key path.
Here's a simple implementation:
extern NSString *const kMyLocalDragType = #"com.whatever.localDragType";
#implementation MyArrayControllerDataSource
.
.
.
#pragma mark - NSTableViewDataSource (Drag & Drop)
+ (NSArray *)dragTypes {
// convenience method returning all class's supported dragTypes
return #[kMyLocalDragType];
}
- (BOOL)tableView:(NSTableView *)tableView writeRowsWithIndexes:(NSIndexSet *)rowIndexes toPasteboard:(NSPasteboard *)pboard {
[pboard declareTypes:[[self class] dragTypes] owner:self];
for (NSString *aDragType in [[self class] dragTypes]) {
if (aDragType == kMyLocalDragType) {
NSData *data = [NSKeyedArchiver archivedDataWithRootObject:rowIndexes]; // we are supporting drag&drop of multiple items selected
[pboard setData:data forType:aDragType];
}
.
. // logic for other dragTypes
.
}
return YES;
}
- (NSDragOperation)tableView:(NSTableView *)tableView validateDrop:(id<NSDraggingInfo>)info proposedRow:(NSInteger)row proposedDropOperation:(NSTableViewDropOperation)dropOperation {
NSArray *dragTypes = [info draggingPasteboard] types];
for (id aDragType in dragTypes) {
if (aDragType == kMyLocalDragType) {
return NSDragOperationCopy;
}
}
.
.// Other logic for accepting drops/affect drop operation
.
}
- (BOOL)tableView:(NSTableView *)tableView acceptDrop:(id<NSDraggingInfo>)info row:(NSInteger)row dropOperation:(NSTableViewDropOperation)dropOperation {
if ([info draggingPasteboard] types] containsObject:kMyLocalDragType]) {
// Retrieve the index set from the pasteboard:
NSData *data = [[info draggingPasteboard] dataForType:kMyLocalDragType];
NSIndexSet *rowIndexes = [NSKeyedUnarchiver unarchiveObjectWithData:data];
NSArray *droppedObjects = [self retrieveFromTableView:tableView objectsAtRows:rowIndexes];
// droppedObjects contains dragged and dropped objects, do what you
// need to do with them, then add them to this dataSource:
[self.content insertObjects:droppedObjects];
[tableView reloadData];
[tableView deselectAll:nil];
return YES;
}
.
. // other logic for accepting drops of other dragTypes supported.
.
}
#pragma mark - Helpers
- (NSArray <NSManagedObject *> *)retrieveFromTableView:(NSTableView *)tableView objectsAtRowIndexes:(NSIndexSet *)rowIndexes {
id dataSource = [tableView dataSource];
if ([dataSource respondsToSelector:#selector(content)]) {
if ([dataSource.content respondsToSelector:#selector(objectsAtIndexes:)]) {
return [datasource content] objectsAtIndexes:rowIndexes];
}
}
return #[]; //We return an empty array in case introspection check failed
}