Xcode 4.4 adds support for Obj-C literals

http://itunes.apple.com/gb/app/xcode/id497799835?mt=12

by BenjieGillam • 14 years ago

46 15 14 years ago

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See http://clang.llvm.org/docs/ObjectiveCLiterals.html for more information, but some examples from that page:

  NSNumber *fortyTwo = @42;             // equivalent to [NSNumber numberWithInt:42]
  NSNumber *piDouble = @3.1415926535;   // equivalent to [NSNumber numberWithDouble:3.1415926535]
  NSNumber *yesNumber = @YES;           // equivalent to [NSNumber numberWithBool:YES]
  NSArray *array = @[ @"Hello", NSApp, [NSNumber numberWithInt:42] ];
  NSDictionary *dictionary = @{
      @"name" : NSUserName(),
      @"date" : [NSDate date],
      @"processInfo" : [NSProcessInfo processInfo]
  };

This, especially the NSArray/NSDictionary stuff, should make coding in Obj-C so much faster and more pleasant - well done LLVM team!

PS: Not sure if the object subscripting stuff is supported yet, but that looks awesome too!

upinsmoke• 14 years ago

Subscripting only on OS X not iOS.

weiran• 14 years ago

You can use them on iOS 5.1 by implementing the methods the subscripts map to on NSArray and NSDictionary (as well as mutable) in categories.

For NSArray:

    - (id)objectAtIndexedSubscript:(NSUInteger)index {
        return [self objectAtIndex:index];
    }

NSMutableArray:

    - (void)setObject:(id)object atIndexedSubscript:(NSUInteger)index {
        if (index < self.count){
            if (object)
                [self replaceObjectAtIndex:index withObject:object];
            else
                [self removeObjectAtIndex:index];
        } else {
            [self addObject:object];
        }
    }

NSDictionary:

    - (id)objectForKeyedSubscript:(id)key {
        return [self objectForKey:key];
    }

NSMutableDictionary:

    - (void)setObject:(id)object forKeyedSubscript:(id)key {
        [self setObject:object forKey:key];
    }

BenjieGillam2• 14 years ago

Apparently OSX 10.8 and iOS 6 bring support for subscripting to native NSArray/NSDictionary, but I think you can add subscripts to your own classes already just by implementing the following methods:

  -(id)objectAtIndexedSubscript:(NSUInteger)index;
  -(void)setObject:(id)object atIndexedSubscript:(NSUInteger)index;

as weiran has shown for NS(Mutable)Array/NS(Mutable)Dictionary.

skibrah• 14 years ago

That functionality is coming with Xcode 4.5

lazerwalker• 14 years ago

The functionality is present for iOS, it just isn't being exposed. If you create a category header file (just header, not implementation) the compiler'll pick up on it and all will work fine.

This isn't my code, but I've been happily using it for a week or so now: https://gist.github.com/3299750

pmjordan2• 14 years ago

Note that if you have

  int foo = 42;
  NSNumber* boxed = @foo; // fails
  NSNumber* boxed = @(foo); // works

One thing that isn't supported but would be extremely useful is a shortcut for NSValue boxing. Fortunately, it's really easy to solve using a short macro, e.g.:

  #define BOXED(val) ({ typeof(val) _tmp_val = (val); [NSValue valueWithBytes:&(_tmp_val) objCType:@encode(typeof(val))]; })
  CGRect rect = {{ 0, 0 }, {100,200}};
  NSValue* boxed = BOXED(rect);

tolmasky2• 14 years ago

I've made that same macro, unfortunately the unboxing is the hard part because you don't know what type the NSValue contains. This is why I was hoping it would be a compiler feature because the compiler could use the surrounding info to figure it out:

    int x = some_nsvalue; // it knows you want an int
    [obj takeDouble:some_nsvalue]; // it knows takeDouble expects a double 
    (CGAffineTransform)some_nsvalue // typecast is the ultimate hint

steipete• 14 years ago

Also see this guide how to use subscripting in Xcode 4.4 http://petersteinberger.com/blog/2012/using-subscripting-wit...

ashcairo2• 14 years ago

Is it possible to downgrade back to 4.4? 4.4.1 seems to crash often now when stepping through my code.

ashcairo2• 14 years ago

https://developer.apple.com/downloads/index.action?name=Xcod...

Xcode 4.4 adds support for Obj-C literals

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