NSHipster-New-Years-2014.md

Greetings, NSHipsters!

As we prepare to increment our NSDateComponents -year by 1, it's time once again for NSHipster end-of-the-year Reader Submissions! Last year, we got some mind-blowing tips and tricks. With the release of iOS 7 & Mavericks, and a year's worth of new developments in the Objective-C ecosystem, there should be a ton of new stuff to write up for this year.

Submit your favorite piece of Objective-C trivia, framework arcana, hidden Xcode feature, or anything else you think is cool, and you could have it featured in the year-end blowout article. Just comment on this gist below!

Here are a few examples of the kind of things I'd like to see:

• Using NSStringFromSelector(@selector()) as a safer way to do KVC / KVO / NSCoding.
• Panic's rather surprising discovery about the internals of the Lightning Digital AV Adapter
• This brilliant write-up deriving block syntax from C declarators by @nilsou, or @lazerwalker's more to-the-point site, "Fucking Block Syntax"

Can't wait to see what y'all come up with!

Protect your class from default initializers by marking init and new as unavailable. You can also provide a custom string that the compiler will display if somebody tries to use one.

-(instancetype) init attribute((unavailable("Please use initWithString")));
+(instancetype) new attribute((unavailable("Please use initWithString")));

In my attempts to avoid learning how to method-swizzle, I came up with a way of "replacing" classes with subclasses.

@implementation NSLayoutManager (JLLayoutManager)

// [NSLayoutManager alloc] will return an instance of  JLLayoutManager.
+ (id)alloc
{
    if ([self class] == [NSLayoutManager class]) {
        return [JLLayoutManager alloc];
    }
    return [super alloc];
}

@end

I wrote the helper function for creating key path from selectors

inline NSString * PTPKeyPathsForKeys(SEL key, ...) {
  if (!key) {
    return nil;
  }
  NSMutableArray *keys = [[NSMutableArray alloc] init];
  va_list args;
  va_start(args, key);
  SEL arg = key;
  do {
    [keys addObject:NSStringFromSelector(arg)];
  } while ((arg = va_arg(args, SEL)));
  va_end(args);

  return [keys componentsJoinedByString:@"."];
}

Usage

NSString *keyPath = PTPKeyPathsForKeys(@selector(data), @selector(name), NULL); // @"data.name"

you should write a Post about the advantage from xcconfig files

yeah xcconfig files @carlj

Recently I discovered a new Foundation class named NSByteCountFormatter, no more custom file size formatters! Documentation.

My favorite self-written hack this year is SPAwait. It emulates the await keyword from C# 4 (or Futures.wait from node.js) by building coroutines using macros, blocks and non-structured case statements (inspired by an old mikeash post). Unfortunately, it doesn't work great with ARC :( while not usable in real life, such structure allows you to write asynchronous code as if it was synchronous, which is absolutely magical and wonderful. Way better than either callbacks or futures.

https://github.com/nevyn/SPAsync/blob/master/include/SPAsync/SPAwait.h

iOS7 has introduced a lot of changes in the API, both deprecating and introducing new methods, in different frameworks.

One way to deal with this is to temporary disable the deprecated warnings in clang with a pragma (where you handle the API differences).

Another way is to use the excellent Deploymate for managing different iOS versions. It analyzes your code and gives you warnings for deprecated/new methods. Like with clang, you can use a pragma to let Deploymate ignore it.

Here is a gist with a few macros to help with checking the iOS version and ignore both clang and Deploymate's warnings.

To use the macros, simply do:

AVAILABLE_API_IF_GREATER_THAN(@“7.0”)
    do_something_only_in_ios7();
AVAILABLE_API_ELSE
    do_something_for_others();
AVAILABLE_API_END