Safe area fix guide for earlier versions of iOS

Safe area layout is introduced in iOS11 but what can we do if we are supporting < iOS 11 and we have a xib view that is initiated in a ViewController and somehow the upper part of the xib view appears behind the NavigationBar??? To fix this, simply add this line in your viewDidLoad.

self.edgesForExtendedLayout = UIRectEdge.init(rawValue: 0)

For more information visit EdgesForExtendedLayout at Apple.

Embed a UIViewController in a UINavigationController Programmatically

We know how to embed a ViewController in a NavigationController in Storyboard. However, I came across a scenario where I had to initiate it programmatically. The code:

let viewController = MyViewController()
let nav = UINavigationController(rootViewController: viewController)
self.navigationController?.present(nav, animated: true, completion: nil)

Unique ID on iOS Devices

Problem!

We all know now that identifierForVendor doesn’t remain unique on iOS Devices. It changes when the user deletes all of the apps from the same vendor.

According to Apple:

The value in this property remains the same while the app (or another app from the same vendor) is installed on the iOS device. The value changes when the user deletes all of that vendor’s apps from the device and subsequently reinstalls one or more of them. The value can also change when installing test builds using Xcode or when installing an app on a device using ad-hoc distribution. Therefore, if your app stores the value of this property anywhere, you should gracefully handle situations where the identifier changes.

Please see Apple Documentation for more information.

Solution

To get the unique Id we need to generate it first through CFUUID and save it on the device using KeyChain, in this case our SwiftKeychainWrapper will do the job. This way, even when the user deletes the app the UUID can be fetched using the UNIQUE_KEY that was originally used to save the UUID.

import UIKit
import SwiftKeychainWrapper

class ViewController: UIViewController {

    @IBOutlet weak var uuidValue: UILabel!
    private let UNIQUE_KEY = "mySuperDuperUniqueId"
    override func viewDidLoad() {
        super.viewDidLoad()
        let uniqueDeviceId: String? = KeychainWrapper.standard.string(forKey: UNIQUE_KEY)
        
        guard uniqueDeviceId != nil else {
            let uuid = generateUuid()
            let saveSuccessful: Bool = KeychainWrapper.standard.set(uuid, forKey: UNIQUE_KEY)
            if saveSuccessful {
                uuidValue.text = uuid
            } else {
                fatalError("Unable to save uuid")
            }
            return
        }
        uuidValue.text = uniqueDeviceId!
    }
    
    private func generateUuid() -> String {
        let uuidRef: CFUUID = CFUUIDCreate(nil)
        let uuidStringRef: CFString = CFUUIDCreateString(nil, uuidRef)
        return uuidStringRef as String
    }
}