blakewatters

Now that the GateGuru team has been developing on the iOS 5 SDK for awhile, I thought I'd pull together some lessons learned.

• Declare your IBOutlet and IBActions within the private category within your implementation file. This makes them visible to interface builder without cluttering up the external interfaces and leaking implementation details.
• Declare your IBOutlet properties as (nonatomic, weak). The weak reference implies a non-owning reference and ARC will nil it as necessary.
• Delegate properties should be (nonatomic, weak) as well.
• The designated initializer for UIView's is initWithFrame: when initialized programmatically. When loaded from a Storyboard or custom Nib, it is initWithCoder:
• The designated initializer for UIViewController's is initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil when initialized programmatically. It is initWithCoder: when loaded from a Storyboard or Nib.

hellerbarde

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs

orip

/*
Usage:

WEAKSELF_T weakSelf = self;
dispatch_async(queue, ^{
  [weakSelf coolStuff];
});
*/
#if __has_feature(objc_arc_weak)
#define WEAKSELF_T __weak __typeof__(self)

mattt

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](http://www.panic.com/blog/the-lightning-di

kristopherjohnson

// Protocol for a type that supports a fromRaw(Int) conversion
// (such as "enum Foo: Int { ... }")
protocol ConvertibleFromRawInt {
    class func fromRaw(raw: Int) -> Self?
}

// Note: Tried to use Swift's standard RawRepresentable protocol rather
// than ConvertibleFromRawInt, but couldn't get it to compile.
// Don't know whether it is a Swift bug or something I was doing wrong.

ishikawa

import Foundation

protocol EndianConvertible {
    typealias IntegerType

    init(bigEndian value: IntegerType)
    init(littleEndian value: IntegerType)

    var bigEndian: IntegerType { get }
    var littleEndian: IntegerType { get }

kristopherjohnson

import UIKit

/// Wrapper for the NSNotification userInfo values associated with a keyboard notification.
///
/// It provides properties that retrieve userInfo dictionary values with these keys:
/// 
/// - UIKeyboardFrameBeginUserInfoKey
/// - UIKeyboardFrameEndUserInfoKey
/// - UIKeyboardAnimationDurationUserInfoKey
/// - UIKeyboardAnimationCurveUserInfoKey

radex

infix operator ??= {
    associativity right
    precedence 90
    assignment
}

func ??= <T>(inout variable: T?, expr: @autoclosure () -> T) {
    if variable == nil {
        variable = expr()
    }

danielchasehooper

#!/bin/sh
find . \( -iname "*.[chm]" -o -iname "*.swift" -o -iname "*.cpp" -o -iname "*.mm" \) -print0 | xargs -0 cat | wc -l

rnystrom

#!/bin/sh
# Example usage
# cd into directory that has @3x images
# ./whatever-you-name-this.sh
# Remember to chmod +x the script

resize () {
	ls *@3x.png | awk '{print("convert "$1" -filter box -resize '$1' "$1)}' | sed 's/@3x/'$2'/2' | /bin/sh	
}