Convert NSArray to NSDictionary

Question

How can I convert an NSArray to an NSDictionary, using an int field of the array's objects as key for the NSDictionary?

Answer 1

Try this magic:

NSDictionary *dict = [NSDictionary dictionaryWithObjects:records                                     forKeys:[records valueForKey:@"intField"]]; 

FYI this is possible because of this built-in feature:

@interface NSArray(NSKeyValueCoding)  /* Return an array containing the results of invoking -valueForKey:  on each of the receiver's elements. The returned array will contain NSNull elements for each instance of -valueForKey: returning nil. */ - (id)valueForKey:(NSString *)key; 

Answer 2

- (NSDictionary *) indexKeyedDictionaryFromArray:(NSArray *)array  {   id objectInstance;   NSUInteger indexKey = 0U;    NSMutableDictionary *mutableDictionary = [[NSMutableDictionary alloc] init];   for (objectInstance in array)     [mutableDictionary setObject:objectInstance forKey:[NSNumber numberWithUnsignedInt:indexKey++]];    return (NSDictionary *)[mutableDictionary autorelease]; }