cheat_sheet.swift

// These are answers I've found on Stack Overflow or solutions I've created myself
// I hope they can help you too

import Foundation
import AVFoundation
import CoreData
import AddressBook
import AddressBookUI

// 1) Create a background with a gradient for your view
// if you're using Storyboards, create a background color
// so you can see your other items in your view if your text is white
// on a blue background, for example. Below example is a light blue

// Put this in viewDidLoad
let gradient: CAGradientLayer = CAGradientLayer()
let arrayColors: [AnyObject] = [
    UIColor(red: 0.302, green: 0.612, blue: 0.961, alpha: 1.000).CGColor,
    UIColor(red: 0.247, green: 0.737, blue: 0.984, alpha: 1.000).CGColor
]

gradient.frame = view.bounds
gradient.colors = arrayColors
view.layer.insertSublayer(gradient, atIndex: 0)



// 2) Play a sound with AVFoundation

// add AVAudioPlayerDelegate to your ViewController like this:
// class ViewController: UIViewController, AVAudioPlayerDelegate { ... }

// declare the player and the error optionals
var avPlayer: AVAudioPlayer?
var error: NSError?

// first line creates a url, which you feed into the player and then play
// use self. with these because your declaration of avPlayer above attached the player
// to the ViewController which is the top-level object & has property ViewContrller.avPlayer
let fileURL: NSURL! = NSBundle.mainBundle().URLForResource("sound_name", withExtension: "wav")
self.avPlayer = AVAudioPlayer(contentsOfURL: fileURL, error: nil)
self.avPlayer?.play()


// 3) How to edit the text of a UIButton
// maybe your button has title "start"
// Normal state is when it's not pressed, when it's just chillin'
buttonName.setTitle("stop", forState: .Normal)


// 4) Setting the value of a textField a few different ways
myTextField.text = "Foo"

// you can edit the value of %.0f for different percision in the decimal, this will return 2, rather than 2.0 or 2.0000
myTextField.text = String(format: "%.0f", (Double(120) / Double(60)))

// convert integer to string
myTextField.text = (5).stringValue


// 5) removing the keyboard
// the code below should be tied to an IBAction most likely
// tap somewhere on the screen, resign first responder
myTextField.resignFirstResponder()


// 6) Focus on a text field
// this is good for submitting a form with a bad value that needs editing
myTextField.becomeFirstResponder()


// 7) Hides the status bar at the top of the screen
override func prefersStatusBarHidden() -> Bool { return true }


// 8) Get last value from CoreData

// fetch last user from coredata
// you must import CoreData at the top of your file to do this
// this assumes your CoreData model has the entity "User", User here can be anything
let appDelegate = (UIApplication.sharedApplication().delegate as AppDelegate)
let managedObjectContext = appDelegate.managedObjectContext!
let request = NSFetchRequest(entityName: "User")
var error: NSError?

// makes sure that objects are in the database before you fetch the last one
let result = managedObjectContext.executeFetchRequest(request, error: &error)
if let objects = result as? [User] {
    if let lastUser = objects.last { ... }
}


// 9) A better way to set objects in CoreData

// UIApplication is our top level selector for the application
// sharedApplication is one and only one (singleton) instance,
// then we get the delegate property
let appDelegate = (UIApplication.sharedApplication().delegate as AppDelegate)
let managedObjectContext = appDelegate.managedObjectContext!

let user = NSEntityDescription.insertNewObjectForEntityForName("User", inManagedObjectContext: managedObjectContext) as User

// store everything from the session in CoreData,
user.name = "Zack Shapiro"
user.hometown = "Baltimore"
user.baseballTeam = "Orioles"

// trigger the save and account for a potential error
var error : NSError?
if !managedObjectContext.save(&error) {
    println("save failed: \(error?.localizedDescription)")
}


// 10) prevent your phone from going to sleep, good if you don't want the user
// getting to the lock screen
UIApplication.sharedApplication().idleTimerDisabled = true


// 11) dismiss the keyboard when pressing return in a UITextView

func textView(textView: UITextView!, shouldChangeTextInRange: NSRange, replacementText: NSString!) {
    if (replacementText == "\n") {
        myTextView.resignFirstResponder()
    }
}


// 12) set a maximum amount of characters in a UITextView
// add UITextViewDelegate to your ViewController like this:
// class EditViewController : UIViewController, UITextViewDelegate {

func textView(textView: UITextView, shouldChangeTextInRange range: NSRange, replacementText text: String) -> Bool {
    let newLength = countElements(textView.text!)  + countElements(text) - range.length
    let maxLength = 140
    
    //return true only if the length is at most the maxLength
    if newLength <= maxLength {
        return true
    }
    
    return false
}


// 13) add person with first, last name, job title and phone number to the AddressBook

func addUserToAddressBook(firstName: String, lastName: String, jobTitle: String, phoneNumber: String){
    func createMultiStringRef() -> ABMutableMultiValueRef {
        let propertyType: NSNumber = kABMultiStringPropertyType
        return Unmanaged.fromOpaque(ABMultiValueCreateMutable(propertyType.unsignedIntValue).toOpaque()).takeUnretainedValue() as NSObject as ABMultiValueRef
    }
    
    let stat = ABAddressBookGetAuthorizationStatus()
    switch stat {
    case .Denied, .Restricted:
        println("no access to addressbook")
    case .Authorized, .NotDetermined:
        var err : Unmanaged<CFError>? = nil
        var addressBook : ABAddressBook? = ABAddressBookCreateWithOptions(nil, &err).takeRetainedValue()
        if addressBook == nil {
            println(err)
            return
        }
        ABAddressBookRequestAccessWithCompletion(addressBook) {
            (granted:Bool, err:CFError!) in
            if granted {
                var newContact:ABRecordRef! = ABPersonCreate().takeRetainedValue()
                var success:Bool = false
                
                //Updated to work in Xcode 6.1
                var error: Unmanaged<CFErrorRef>? = nil
                //Updated to error to &error so the code builds in Xcode 6.1
                success = ABRecordSetValue(newContact, kABPersonFirstNameProperty, firstName, &error)
                success = ABRecordSetValue(newContact, kABPersonLastNameProperty, lastName, &error)
                success = ABRecordSetValue(newContact, kABPersonJobTitleProperty, jobTitle, &error)
                
                if (phoneNumber != nil) {
                    let propertyType: NSNumber = kABMultiStringPropertyType
                    
                    var phoneNumbers: ABMutableMultiValueRef =  createMultiStringRef()
                    var phone = ((phoneNumber as String).stringByReplacingOccurrencesOfString(" ", withString: "") as NSString)
                    
                    ABMultiValueAddValueAndLabel(phoneNumbers, phone, kABPersonPhoneMainLabel, nil)
                    success = ABRecordSetValue(newContact, kABPersonPhoneProperty, phoneNumbers, &error)
                    
                    
                }
                
                success = ABRecordSetValue(newContact, kABPersonNoteProperty, "added via iPhone App", &error)
                success = ABAddressBookAddRecord(addressBook, newContact, &error)
                success = ABAddressBookSave(addressBook, &error)
                
            } else {
                println(err)
            }
        }
    }
    
}

// 14) Use hex color codes for UIColor
// adding this code snippet will enable you to use them like this:
// let purpleColor : UIColor = UIColor.fromRGB(0x71679B) whereas
// everything after the 0x is the hex color code


extension UIColor {
    
    class func fromRGB(rgb:UInt32) -> UIColor {
        return UIColor(
            red: CGFloat((rgb & 0xFF0000) >> 16) / 255.0,
            green: CGFloat((rgb & 0x00FF00) >> 8) / 255.0,
            blue: CGFloat(rgb & 0x0000FF) / 255.0,
            alpha: CGFloat(1.0)
        )
    }
    
}

// 15) NSUserDefaults, save and retrieve values (can store more types than just those shown in this example)
// Typically used to save user preferences for subsequent app launches

let sampleObject = "Jasdev", sampleInt = 1, sampleBool = true
let objectKey = "objectKey", intKey = "intKey", boolKey = "boolKey"

// Set defaults
NSUserDefaults.standardUserDefaults().setObject(sampleObject, forKey: objectKey)
NSUserDefaults.standardUserDefaults().setInteger(sampleInt, forKey: intKey)
NSUserDefaults.standardUserDefaults().setBool(sampleBool, forKey: boolKey)

NSUserDefaults.standardUserDefaults().synchronize()

// Retrieve defaults
let object = NSUserDefaults.standardUserDefaults().objectForKey(objectKey) as String
let int = NSUserDefaults.standardUserDefaults().integerForKey(intKey)
let bool = NSUserDefaults.standardUserDefaults().boolForKey(boolKey)

// 16) Create a NSAttributed String
// Styling a String with things like lineHeight is a bit harder
// than you might think.  For example: let's take a String and
// use Avenir Light 28pt font with 6pt lineSpacing

// set the properties
let font = UIFont(name: "Avenir-Light", size: 28)
let style = NSMutableParagraphStyle()
style.lineSpacing = 6

let attributes = [NSParagraphStyleAttributeName : style, NSFontAttributeName: font!]

// Replace Example text with the prefered text or string.
var attributedString = NSAttributedString(string: "Example text", attributes:attributes)

// 17) Make a Screenshot

func makeScreenshot() -> UIImage {
    UIGraphicsBeginImageContext(self.view.bounds.size)
    
    self.view.layer.renderInContext(UIGraphicsGetCurrentContext())
    var viewImage: UIImage = UIGraphicsGetImageFromCurrentImageContext()
    
    UIGraphicsEndImageContext()
    
    return viewImage
}

// more comming soon