Question

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alloc, init, and new in Objective-C

I am a little confused about [Class new] and [[Class alloc] init]. I have defined an object content using [Class new] and [[Class alloc] init].

(1). NSMutableArray *content = [NSMutableArray new];
(2). NSMutableArray *content = [[NSMutableArray alloc] init];

My question is about the differences between [Class new] and [[Class alloc] init]. For me, (1) and (2) are similar. If (1) and (2) are similar, then why do we use [[Class alloc] init] most of the time, compared to [Class new]? I think that there must be some difference.

Kindly explain the differences, pros & cons of both?

Answer 1

Alloc: Class method of NSObject. Returns a new instance of the receiving class.

Init: Instance method of NSObject. Implemented by subclasses to initialize a new object (the receiver) immediately after memory for it has been allocated.

New: Class method of NSObject. Allocates a new instance of the receiving class, sends it an init message, and returns the initialized object.

Release: Instance method of NSObject delegate. Decrements the receiver’s reference count.

Autorelease: Instance method of NSObject delegate. Adds the receiver to the current autorelease pool.

Retain: Instance method of NSObject delegate. Increments the receiver’s reference count.

Copy: Instance method of NSObject delegate. Returns a new instance that’s a copy of the receiver.

So to conclude we can say that

alloc goes with init

new = alloc + init