ArrayHelpers.swift

extension Array {
    
    func first() -> Element? {
        if isEmpty {
            return nil
        }
        return self[0]
    }
    
    func last() -> Element? {
        if isEmpty {
            return nil
        }
        let index = count - 1
        return self[index]
    }
    
    func head() -> Element? {
        return first()
    }
    
    func tail() -> [Element]? {
        if isEmpty || count == 1 {
            return nil
        }
        let range: Range<Int> = Range(start: 1, end: count)
        let slice = self[range]
        return Array(slice)
    }
    
}

DispatchAfter.swift

// Nice helper function for dispatch_after
func dispatch_after_delay(delay: NSTimeInterval, queue: dispatch_queue_t, block: dispatch_block_t) {
    let time = dispatch_time(DISPATCH_TIME_NOW, Int64(delay * Double(NSEC_PER_SEC)))
    dispatch_after(time, queue, block)
}

// Or you can do it the old way
let offset = 2.0
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, Int64(offset * Double(NSEC_PER_SEC))), dispatch_get_main_queue(), {
    // Do something
})

NotificationHelpers.swift

import UIKit

extension NSNotification {
   
    func cmd_beginKeyboardAnimation() {
        UIView.beginAnimations(nil, context: nil)
        UIView.setAnimationDuration(cmd_keyboardAnimationDuration())
        UIView.setAnimationCurve(cmd_keyboardAnimationCurve())
    }
    
    func cmd_commitKeyboardAnimation() {
        UIView.commitAnimations()
    }
    
    func cmd_performAnimationsWithKeyboardAnimation(block: (Void) -> Void) {
        cmd_beginKeyboardAnimation()
        block()
        cmd_commitKeyboardAnimation()
    }
    
    func cmd_keyboardFrameInView(view: UIView) -> CGRect {
        let keyboardFrame = cmd_keyboardFrameEnd()
        return view.convertRect(keyboardFrame, fromView: view);
    }
    
    func cmd_keyboardFrameEnd() -> CGRect {
        return userInfo[UIKeyboardFrameEndUserInfoKey].CGRectValue()
    }
    
    func cmd_keyboardAnimationDuration() -> NSTimeInterval {
        return userInfo[UIKeyboardAnimationDurationUserInfoKey] as NSTimeInterval
    }
    
    func cmd_keyboardAnimationCurve() -> UIViewAnimationCurve {
        var curve = UIViewAnimationCurve.Linear
        userInfo[UIKeyboardAnimationCurveUserInfoKey].getValue(&curve)
        return curve
    }
    
}

NSDate+Helpers.swift

import Foundation

extension NSDate: Comparable {
    
}

func <=(lhs: NSDate, rhs: NSDate) -> Bool {
    return lhs == rhs || lhs < rhs
}

func >=(lhs: NSDate, rhs: NSDate) -> Bool {
    return lhs == rhs || lhs > rhs
}

func >(lhs: NSDate, rhs: NSDate) -> Bool {
    let result = lhs.compare(rhs)
    return result == NSComparisonResult.OrderedDescending
}

/**
 This method is not required by the Comparable protocol but Xcode 6 beta 3
 would not compile without it.
*/
func <(lhs: NSDate, rhs: NSDate) -> Bool {
    let result = lhs.compare(rhs)
    return result == NSComparisonResult.OrderedAscending
}

func ==(lhs: NSDate, rhs: NSDate) -> Bool {
    return lhs.isEqualToDate(rhs)
}

/**
 Operators for incrementing dates.
*/

func +(date: NSDate, interval: NSTimeInterval) -> NSDate {
    return date.dateByAddingTimeInterval(interval)
}

@assignment func +=(inout date: NSDate, interval: NSTimeInterval) {
    date = date + interval
}

func -(date: NSDate, interval: NSTimeInterval) -> NSDate {
    return date.dateByAddingTimeInterval(-interval)
}

@assignment func -=(inout date: NSDate, interval: NSTimeInterval) {
    date = date - interval
}

Singleton.swift

class func sharedClient() -> CanaryClient {
    struct Static {
        static var instance: CanaryClient?
        static var token: dispatch_once_t = 0
    }
    dispatch_once(&Static.token, {
        Static.instance = CanaryClient()
    })
    return Static.instance!
}

StringHelpers.swift

@infix func * (template: String, count: Int) -> String {
    var string: String = ""
    for i in 0..count {
        string += template
    }
    return string
}

Typedefs.swift

// You can make aliases for closure types
typealias AccountStoreMultipleAccountsCompletion = ([ACAccount]?, NSError?) -> ()
typealias AccountStoreSingleAccountCompletion = (ACAccount?, NSError?) -> ()

// Or embed them in a type
class AccountStore {
    typealias MultipleAccountsCompletion = ([ACAccount]?, NSError?) -> ()
    typealias SingleAccountCompletion = (ACAccount?, NSError?) -> ()
}