iOS 6 PTL: Chapter 2 Errata

Posted by iosptl on Dec 16, 2012 in Book Updates | 0 comments

We made a typo in Chapter 2, section Collection Literals.

The syntax for creating a new NSDictionary was written as

 
NSDictionary *dict = @[@"key1":@"value1", @"key2":@"value2", @"key2":@"value2"]

The correct syntax is

 
NSDictionary *dict = @{
@"key1":@"value1", 
@"key2":@"value2", 
@"key3":@"value3"
}

Curly braces are used for creating dictionaries and square brackets are used for creating arrays.

In Object Subscripting section,
when you access a element in an array using a subscript, you get a NSNumber

So the correct code that compiles without a warning is as below.

NSArray *array = @[@1, @2, @3, @4, @5]
NSNumber *elementAt3 = array[3];

Thanks to Luca Bernardi for pointing this out.

–
Mugunth