Use of alloc init instead of new

Question

Learning Objective-C and reading sample code  I notice that objects are usually created using this method   SomeObject  myObject     SomeObject alloc  init     instead of   SomeObject  myObject    SomeObject new     Is there a reason for this  as I have read that they are equivalent

User · Accepted Answer

There are a bunch of reasons here  http   macresearch org difference-between-alloc-init-and-new  Some selected ones are    new doesn t support custom initializers  like initWithString  alloc-init is more explicit than new   General opinion seems to be that you should use whatever you re comfortable with

User · Answer

Very old question  but I ve written some example just for fun     maybe you ll find it useful      import  InitAllocNewTest h    implementation InitAllocNewTest    id alloc      NSLog   Allocating           return  super alloc      - id init      NSLog   Initializing           return  super init       end   In main function both statements     InitAllocNewTest alloc  init     and    InitAllocNewTest new     result in the same output    2013-03-06 16 45 44 125 XMLTest 18370 207  Allocating    2013-03-06 16 45 44 128 XMLTest 18370 207  Initializing

User · Answer

Frequently  you are going to need to pass arguments to init and so you will be using a different method  such as   SomeObject alloc  initWithString    Foo    If you re used to writing this  you get in the habit of doing it this way and so   SomeObject alloc  init  may come more naturally that  SomeObject new

User · Answer

new is equivalent to  alloc -init in Apple s NSObject implementation  It is highly unlikely that this will ever change  but depending on your paranoia level  Apple s documentation for  new appears to allow for a change of implementation  and breaking the equivalency  in the future  For this reason  because  explicit is better than implicit  and for historical continuity  the Objective-C community generally avoids  new  You can  however  usually spot the recent Java comers to Objective-C by their dogged use of  new

User · Answer

For a side note  I personally use  Foo new  if I want something in init to be done without using it s return value anywhere  If you do not use the return of   Foo alloc  init  anywhere then you will get a warning  More or less  I use  Foo new  for eye candy

User · Answer

I am very late to this but I want to mention that that new is actually unsafe in the Obj-C with Swift world  Swift will only create a default init method if you do not create any other initializer  Calling new on a swift class with a custom initializer will cause a crash  If you use alloc init then the compiler will properly complain that init does not exist

User · Answer

If new does the job for you  then it will make your code modestly smaller as well   If you would otherwise call   SomeClass alloc  init  in many different places in your code  you will create a Hot Spot in new s implementation - that is  in the objc runtime - that will reduce the number of your cache misses   In my understanding  if you need to use a custom initializer use   SomeClass alloc  initCustom    If you don t  use  SomeClass new

User · Answer

One Short Answere is    Both are same  But  new  only works with the basic  init  initializer  and will not work with other initializers  eg initWithString

[objective-c] Use of alloc init instead of new

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