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iOS Objective-C Basics (Retired) Beyond the Basics Alloc and Init

Ricky Su
Ricky Su
2,415 Points
Posted by Ricky Su
Ricky Su
2,415 Points

What does init do when it doesn't put any real data to initialize the allocated memory?

I understand initWithInt will put Integer number to the memory, but what if init without any value or data?

For example, NSNumber *n = [[NSNumber alloc] init]

Is init a must here?

1 Answer

Stone Preston
Stone Preston
42,016 Points
Stone Preston
Stone Preston
42,016 Points

if you just use 

NSNumber *n = [[NSNumber alloc] init]

n would be a properly allocated and initialized object, however its value is simply null

if you use 

NSNumber *n = [[NSNumber alloc] initWithInt:2];

n would be a properly allocated and initialized object, and its value would be 2.

calling init is always a must after alloc (the init method what returns the object, sets up default values, etc) . alloc only allocates the chunk of memory to be used. Its good practice to always call alloc and init together