Modern Objective-C

Literals

Modern Objective C provides ways to reduce amount of code you need to initialize some common types. This new way is very similar to how NSString objects are initialized with constant strings.

NSNumber

Old way:

NSNumber *number = [NSNumber numberWithInt:25];

Modern way:

NSNumber *number = @25;

Note: you can also store BOOL values in NSNumber objects using @YES, @NO or @(someBoolValue);

NSArray

Old way:

NSArray *array = [[NSArray alloc] initWithObjects:@"One", @"Two", [NSNumber numberWithInt:3], @"Four", nil];

Modern way:

NSArray *array = @[@"One", @"Two", @3, @"Four"];

NSDictionary

Old way:

NSDictionary *dictionary = [NSDictionary dictionaryWithObjectsAndKeys: array, @"Object", [NSNumber numberWithFloat:1.5], @"Value", @"ObjectiveC", @"Language", nil];

Modern way:

NSDictionary *dictionary = @{@"Object": array, @"Value": @1.5, @"Language": @"ObjectiveC"};

Container subscripting

In modern Objective C syntax you can get values from NSArray and NSDictionary containers using container subscripting.

Old way:

NSObject *object1 = [array objectAtIndex:1];
NSObject *object2 = [dictionary objectForKey:@"Value"];

Modern way:

NSObject *object1 = array[1];
NSObject *object2 = dictionary[@"Value"];

You can also insert objects into arrays and set objects for keys in dictionaries in a cleaner way:

Old way:

// replacing at specific index
[mutableArray replaceObjectAtIndex:1 withObject:@"NewValue"];
// adding a new value to the end
[mutableArray addObject:@"NewValue"];

[mutableDictionary setObject:@"NewValue" forKey:@"NewKey"];

Modern way:

mutableArray[1] = @"NewValue";
mutableArray[[mutableArray count]] = @"NewValue";

mutableDictionary[@"NewKey"] = @"NewValue";