NSHipster Call for Tips & Tricks!

NSHipster-Call-For-Tricks-And-Tips.md

Howdy howdy, NSHipsters!

If you alloc init an NSCalendar, you'll notice that New Year's Eve falls on a Monday this year, a.k.a. "the day NSHipster is published every week". What fun!

So in celebration of the upcoming year++, I thought it'd be fun to compile a list of some of your favorite tips and tricks of the trade. 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:

• StaticObjcMethods from [Apple]((http://developer.apple.com/library/mac/#samplecode/CocoaTipsAndTricks/Introduction/Intro.html): Demonstrates how to use static Objective-C methods that have access to ivars.
• NSArray Slicing from Mike Ash: A sugary syntax for slicing array, with a clever use of subscripting.
• Texts From Xcode: Absolutely brilliant--makes me laugh every time. A must-follow on Twitter or Tumblr.

Again, just comment on this Gist below with your submission.

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

These are all awesome, guys. Thanks for the great tips! Keep it up!

See function static id _target(id autoContentAccessingProxy) for accessing a private ivar. You should obviously never ship your app with such code but it may be helpful for debugging.

extern NSString *const and weak linking does’t work the way you think it works, from https://gist.github.com/3725528:

#import <Social/Social.h>

/* Compiled with iOS 6 SDK
 * Social.framework weak linked (Optional)
 * Run on iOS 5.1 (simulator and device)
 * Output is:
 * 0x0
 * About to crash
 * +++ EXC_BAD_ACCESS +++
 */

int main(int argc, char *argv[])
{
    @autoreleasepool
    {
        NSLog(@"%p", &SLServiceTypeFacebook);
        if (&SLServiceTypeFacebook)
        {
            NSLog(@"About to crash");
            NSString *serviceType = SLServiceTypeFacebook; // crashes here with EXC_BAD_ACCESS (code=2, address=0x0)
            NSLog(@"Not reached %@", serviceType);
        }
    }
    return 0;
}

Reverse-engineered implementation of -[NSString isEqual:] and -[NSString isEqualToString:]

Using NSPropertyListSerialization to implement base64 encoding and decoding in less than 50 lines with support for iOS 2.0 and OS X 10.5.

How about associated objects? You know it’s going down when you see this at the top of one of my files:

#import <objc/runtime.h>

static const void *kMyKey = &kMyKey;

In iOS 6 you can animate a constant property in NSLayoutConstraint:

viewConstraint.constant = ConstantValueFrom;
[view layoutIfNeeded];

viewConstraint.constant = ConstantValueTo;
[view setNeedsUpdateConstraints];

[UIView animateWithDuration:ConstantAnimationDuration animations:^{
     [view layoutIfNeeded];
}];

Printing NSCache usage information (tested on iOS only):

extern void cache_print(void *cache);

- (void) printCache:(NSCache *)cache
{
    cache_print(*((void **)(__bridge void *)cache + 3));
}

Use for debugging only!

Thanks again, everyone, for your great submissions! These have now been compiled into this special New Year's Eve Edition of NSHipster. Cheers!