Objective-C Programming: The Big Nerd Ranch Guide

NSMutableArray

An instance of NSMutableArray is similar to an instance of NSArray, but you can add, remove, and reorder pointers. (NSMutableArray is a subclass of NSArray. You will learn about subclasses in Chapter 20.)

Change your program to use an NSMutableArray and methods from the NSMutableArray class:

#import <Foundation/Foundation.h>

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

        // Create three NSDate objects
        NSDate *now = [NSDate date];
        NSDate *tomorrow = [now dateByAddingTimeInterval:24.0 * 60.0 * 60.0];
        NSDate *yesterday = [now dateByAddingTimeInterval:-24.0 * 60.0 * 60.0];

        // Create an array containing all three
        NSArray *dateList = @[now, tomorrow, yesterday];

        // Create an empty mutable array
        NSMutableArray ...