Objective-C Programming: The Big Nerd Ranch Guide

alloc and init

There is one case where it is always right and proper to nest two message sends. You always nest the messages alloc and init.

The alloc method is a class method that every class has. It returns a pointer to a new instance that needs to be initialized. An uninitialized instance may exist in memory, but it is not ready to receive messages. The init method is an instance method that every class has. It initializes an instance so that it is ready to work.

Practice using nested messages in your program. Create an NSDate object by sending alloc and init messages instead of the date message.

#import <Foundation/Foundation.h>

int main (int argc, const char * argv[])
{
    @autoreleasepool {

        NSDate *now = [NSDate date]; ...