Does NSMutableArray arrayWithArray compare the same as mutableCopy NSArray?

Question

Given the following code example, is the newMutableArrray variable different depending on two different initializations or the same?

 NSArray *originalArray = @[obj1, obj2, oj3]; NSMutableArray *newMutableArray = nil; if (thereIsSomeDifference) { newMutableArray = [NSMutableArray arrayWithArray:originalArray]; } else { newMutableArray = [originalArray mutableCopy]; } 

Answer 1

An array is equal to another array (isEqualToArray: selector) if they have the same objects (in the same order). This is checked using the isEqual: method (regardless of the variable array or not).

They are the same, one or the other initialization does not matter. Make sure this is the result of registering isEqualToArray :.

 NSArray *originalArray = @[obj1, obj2, oj3]; NSMutableArray *newMutableArray = nil; newMutableArray = [NSMutableArray arrayWithArray:originalArray]; thereIsSomeDifference= ![newMutableArray isEqualToArray: [originArray mutableCopy] ]; 

Note that the comparison will be true even if you compare it with a non-volatile copy.

Answer 2

NOT!!! There are two differences between these initializations:

• Keep counter: in the first case you get an object with auto-implementation, in the second case you get a saved object, you need to free it after (this does not apply to ARC)

• If originalArray is zero, in the first case you get a mutable array with 0 element, in the second case you get zero (because sending a message to nil returns zero). In your example, it is clear that originalArray is not zero, but in real life you can achieve this case (I just dealt)

Answer 3

No, their result is exactly the same.
Only initialization is different

Answer 4

To answer, we must define "sameness." These two sides will have different collections side by side, but they will be the same if they point to the same elements.

In other words:

 initA = [NSMutableArray arrayWithArray:originalArray]; initB = [originalArray mutableCopy]; if (initA == initB) { // unreachable, because the pointers differ } // however if ([initA isEqualToArray:initB]) { // will be true // because for (int i=0; i<initA.count; i++) { if ([initA objectAtIndex:i] == [initB objectAtIndex:i]) { NSLog(@"this will log every element %@ in the arrays", [initA objectAtIndex:i]); } } }