There is no “native” array or dictionary type in Core Data. You can store an NSArray or an NSDictionary as a transformable attribute. This will use the NSCoding to serialize the array or dictionary to an NSData attribute (and appropriately deserialize it upon access). The advantage of this approach is that it’s easy. The downside … Read more
NSString * result = [[array valueForKey:@”description”] componentsJoinedByString:@””];
There is a much easier solution, if you take advantage of the built-in reverseObjectEnumerator method on NSArray, and the allObjects method of NSEnumerator: NSArray* reversedArray = [[startArray reverseObjectEnumerator] allObjects]; allObjects is documented as returning an array with the objects that have not yet been traversed with nextObject, in order: This array contains all the remaining … Read more
NSArray *array = [mutableArray copy]; Copy makes immutable copies. This is quite useful because Apple can make various optimizations. For example sending copy to a immutable array only retains the object and returns self. If you don’t use garbage collection or ARC remember that -copy retains the object.
The generally-preferred code for 10.5+/iOS. for (id object in array) { // do something with object } This construct is used to enumerate objects in a collection which conforms to the NSFastEnumeration protocol. This approach has a speed advantage because it stores pointers to several objects (obtained via a single method call) in a buffer … Read more