austinzheng

import Foundation

protocol SomeDelegateProtocol : class {
    func firstFunc() -> String
    func secondFunc() -> Bool
    func thirdFunc() -> Self
}

class MyClass {
    weak var delegate : SomeDelegateProtocol?

nicklockwood

Suppose we want to add support for a new iOS 8 API in our framework that replaces an older iOS 7 API. There are a few problems we might face:

1. The new API will crash if we call it on iOS 7
2. The new API won't compile if we build it using the iOS 7 SDK
3. The old API will raise a deprecation warning if built with a deployment target of iOS 8 and up

These three problems require three different technical solutions:

1. We can avoid calling the new API on an old OS version by using runtime detection (e.g. respondsToSelector:)
2. We can avoid compiling new APIs on old SDKs using the __IPHONE_OS_VERSION_MAX_ALLOWED macro

rgcottrell

class Singleton {
    class var sharedInstance: Singleton {
        struct Static {
            static var token: dispatch_once_t = 0
            static var instance: Singleton!
        }
        dispatch_once(&Static.token) {
            Static.instance = Singleton()
        }
        return Static.instance

calebd

extension Array {
    
    func first() -> Element? {
        if isEmpty {
            return nil
        }
        return self[0]
    }
    
    func last() -> Element? {

prendio2

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    
    NSIndexPath *selectedRowIndexPath = [self.tableView indexPathForSelectedRow];
    if (selectedRowIndexPath) {
        [self.tableView deselectRowAtIndexPath:selectedRowIndexPath animated:YES];
        [[self transitionCoordinator] notifyWhenInteractionEndsUsingBlock:^(id<UIViewControllerTransitionCoordinatorContext> context) {
            if ([context isCancelled]) {
                [self.tableView selectRowAtIndexPath:selectedRowIndexPath animated:NO scrollPosition:UITableViewScrollPositionNone];

jverkoey

// Add this to your app delegate.

// Neither `UINavigationController` nor `UITabBarController` have the slightest decency to ask their
// visible view controller whether IT would like to rotate and just go on and do whatever the hell
// they please. This'll show 'em.
- (NSUInteger)application:(UIApplication *)application supportedInterfaceOrientationsForWindow:(UIWindow *)window {
  UIViewController* topViewController = window.rootViewController;

  do {
    // Navigate modal controllers.

raven

<?xml version="1.0" encoding="UTF-8"?>
<Bucket
   type = "2"
   version = "2.0">
   <Breakpoints>
      <BreakpointProxy
         BreakpointExtensionID = "Xcode.Breakpoint.SymbolicBreakpoint">
         <BreakpointContent
            shouldBeEnabled = "Yes"
            ignoreCount = "0"

myell0w

BOOL MTDIsBoldTextEnabled(void) {
    static BOOL boldTextEnabled = NO;

    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        // Hack that checks if the "bold text" flag in the accessibility settings is enabled
        UIFont *font = [UIFont preferredFontForTextStyle:UIFontTextStyleBody];
        boldTextEnabled = [font.fontName rangeOfString:@"MediumP4"].location != NSNotFound;
    });

kyleve

/**
 Provides the ability to verify key paths at compile time.
 
 If "keyPath" does not exist, a compile-time error will be generated.
 
 Example:
    // Verifies "isFinished" exists on "operation".
    NSString *key = SQKeyPath(operation, isFinished);
 
    // Verifies "isFinished" exists on self.

steipete

static BOOL PSPDFIsDevelopmentBuild(void) {
#if TARGET_IPHONE_SIMULATOR
    return YES;
#else
    static BOOL isDevelopment = NO;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        // There is no provisioning profile in AppStore Apps.
        NSData *data = [NSData dataWithContentsOfFile:[NSBundle.mainBundle pathForResource:@"embedded" ofType:@"mobileprovision"]];
        if (data) {