Do Swift-based applications work on OS X 10.9/iOS 7 and lower?

Question or problem with Swift language programming:

Will Swift-based applications work on OS X 10.9 (Mavericks)/iOS 7 and lower?

For example, I have a machine running OS X 10.8 (Mountain Lion), and I am wondering if an application I write in Swift will run on it.

Or what i should have to create a Swift application using Mac OS?

How to solve the problem:

Solution 1:

I just tested it for you, Swift applications compile into standard binaries and can be run on OS X 10.9 and iOS 7.

---

Simple Swift application used for testing:

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: NSDictionary?) -> Bool {
    self.window = UIWindow(frame: UIScreen.mainScreen().bounds)

    var controller = UIViewController()
    var view = UIView(frame: CGRectMake(0, 0, 320, 568))
    view.backgroundColor = UIColor.redColor()
    controller.view = view

    var label = UILabel(frame: CGRectMake(0, 0, 200, 21))
    label.center = CGPointMake(160, 284)
    label.textAlignment = NSTextAlignment.Center
    label.text = "I'am a test label"
    controller.view.addSubview(label)

    self.window!.rootViewController = controller
    self.window!.makeKeyAndVisible()
    return true
}

Solution 2:

Swift code can be deployed to OS X 10.9 and iOS 7.0. It will usually crash at launch on older OS versions.

Solution 3:

Apple has announced that Swift apps will be backward compatible with iOS 7 and OS X Mavericks. The WWDC app is written in Swift.

Solution 4:

Update – As per Xcode 6 Beta 4

iOS 7 and OS X 10.9 minimum deployment target
The Swift compiler and Xcode now enforce a minimum deployment target of iOS 7 or OS X
Mavericks. Setting an earlier deployment target results in a build failure.

From Xcode 6 release note

So my previous answer(Shown below) will not be applicable to any further development. Swift will no longer available for iOS6 and below

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A Swift application can be run on iOS 6. Even though many people are saying that Swift will support only iOS 7+ and OS X 10.9+, from my experience it’s not.

I have tested a simple application written completely in Swift in an iOS 6 device. It works perfectly fine. As Apple says, Swift code is binary compatible with Objective-C code. It uses the same compiler and runtime to create the binary.

Here is the code I have tested:

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {

        super.viewDidLoad()

        let button   = UIButton.buttonWithType(UIButtonType.System) as UIButton
        button.frame = CGRectMake(100, 100, 100, 50)
        button.backgroundColor = UIColor.greenColor()
        button.setTitle("Test Button", forState: UIControlState.Normal)
        button.addTarget(self, action: "buttonTapped:", forControlEvents: UIControlEvents.TouchUpInside)

        self.view.addSubview(button)
    }

    func buttonTapped(sender: UIButton!) {
        println("buttonTapped")
    }
}

It is a simple application, just adding a button programmatically. My application contains only two files, AppDelegate.swift and ViewController.swift.

So if you are not using any new APIs added as part of the iOS 8 SDK or some Swift specific APIs (corresponding API is not available for Objective-C) your application will seamlessly work on iOS 6 or later (tested and working), even on iOS 5 (not tested). Most of the APIs in Swift are just the replacement of the existing Objective-C APIs. In fact they are the same in binary.

Note: As per Xcode 6 beta 4 for swift apps deployment target should be iOS 7 or OS X 10.9(see the above update). So swift will no longer available for iOS6 and below

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Solution 5:

In brief:

Swift based applications can target back to OS X Mavericks or iOS 7 with that same app.

How is it possible ?

Xcode embeds a small Swift runtime library within your app’s bundle. Because the library is embedded, your app uses a consistent version of Swift that runs on past, present, and future OS releases.

Why should I trust this answer ?

Because I am not saying this answer as one apple guy told me in twitter or I wrote hello world and tested it.

I took it from apple developer blog.

so you can trust this.

Hope this helps!