UIAlertView/UIAlertController iOS 7 and iOS 8 compatibility

Question

The detection pattern is identical to the Objective-C style.

You need to detect whether the current active runtime has the ability to instantiate this class

if objc_getClass("UIAlertController") != nil {

     println("UIAlertController can be instantiated")

      //make and use a UIAlertController

 }
 else {

      println("UIAlertController can NOT be instantiated")

      //make and use a UIAlertView
}

Don't try and work out this based on the OS version. You need to detect abilities NOT OS.

EDIT

The original detector for this answer NSClassFromString("UIAlertController") fails under -O optimisation so its been changed to the current version which does work for Release builds

EDIT 2

NSClassFromString is working at all optimisations in Xcode 6.3/Swift 1.2

For non-swift code, pure objective-C do this

if ([UIAlertController class])
    {
        // use UIAlertController
        UIAlertController *alert= [UIAlertController
                                      alertControllerWithTitle:@"Enter Folder Name"
                                      message:@"Keep it short and sweet"
                                      preferredStyle:UIAlertControllerStyleAlert];

        UIAlertAction* ok = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault
                                                   handler:^(UIAlertAction * action){
                                                       //Do Some action here
                                                       UITextField *textField = alert.textFields[0];
                                                       NSLog(@"text was %@", textField.text);

                                                   }];
        UIAlertAction* cancel = [UIAlertAction actionWithTitle:@"Cancel" style:UIAlertActionStyleDefault
                                                       handler:^(UIAlertAction * action) {

                                                           NSLog(@"cancel btn");

                                                           [alert dismissViewControllerAnimated:YES completion:nil];

                                                       }];

        [alert addAction:ok];
        [alert addAction:cancel];

        [alert addTextFieldWithConfigurationHandler:^(UITextField *textField) {
            textField.placeholder = @"folder name";
            textField.keyboardType = UIKeyboardTypeDefault;
        }];

        [self presentViewController:alert animated:YES completion:nil];

    }
    else
    {
        // use UIAlertView
        UIAlertView* dialog = [[UIAlertView alloc] initWithTitle:@"Enter Folder Name"
                                                         message:@"Keep it short and sweet"
                                                        delegate:self
                                               cancelButtonTitle:@"Cancel"
                                               otherButtonTitles:@"OK", nil];

        dialog.alertViewStyle = UIAlertViewStylePlainTextInput;
        dialog.tag = 400;
        [dialog show];

    }

I was annoyed that I kept having to write out both situations, so I wrote a compatible UIAlertController that works for iOS 7 as well so I just threw it up on GitHub. I did my best to replicate the (much better) methods of adding buttons and actions of the UIAlertController. Works with both Objective-C and Swift. I'm posting this as I found this question when searching on Google and figured it could be helpful for others.

https://github.com/BayPhillips/compatible-alert-controller

You can resolve your issue using this code :-

var device : UIDevice = UIDevice.currentDevice()!;
        var systemVersion = device.systemVersion;
        var iosVerion : Float = systemVersion.bridgeToObjectiveC().floatValue;
        if(iosVerion < 8.0) {
            let alert = UIAlertView()
            alert.title = "Noop"
            alert.message = "Nothing to verify"
            alert.addButtonWithTitle("Click")
            alert.show()
        }else{
            var alert : UIAlertController = UIAlertController(title: "Noop", message: "Nothing to verify", preferredStyle: UIAlertControllerStyle.Alert)
            alert.addAction(UIAlertAction(title: "Click", style:.Default, handler: nil))
            self.presentViewController(alert, animated: true, completion: nil)
        }

and UIKit had to be marked Optional rather than Required.

Courtsey :- Alert that can work on iOS 7 and iOS 8

Swift 2.0

 if #available(iOS 8.0, *) {

 } else {

 }

If this is shared code, and there is the possibility that the code can be used in an iOS 8 extension (where UIAlertView and UIActionSheet are restricted APIs) as well as iOS 7, where UIAlertController does not exist, have a look at: JVAlertController

It is an API-compatible back-port of UIAlertController to iOS 7, that I undertook to make SDK code safe for use in both iOS 7 and iOS 8 extensions.