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iOS Build a Playlist Browser with Swift Working With Multiple View Controllers Recap of iOS Basics

Josh Milbrandt
Josh Milbrandt
6,209 Points
Posted by Josh Milbrandt
Josh Milbrandt
6,209 Points

App crashes using view.backgroundColor

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var aButton: UIButton!
    override func viewDidLoad() {
        super.viewDidLoad()
        aButton.setTitle("Press me!", forState: .Normal)
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    @IBAction func buttonPressed() {
        view.backgroundColor = UIColor.orangeColor()
    }

}

using this code and changing nothing else I get the following error:

2015-05-11 21:52:04.187 Algorythm[7664:278512] -[Algorythm.ViewController buttonPressed:]: unrecognized selector sent to instance 0x7fb69a5b9fd0
2015-05-11 21:52:04.340 Algorythm[7664:278512] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[Algorythm.ViewController buttonPressed:]: unrecognized selector sent to instance 0x7fb69a5b9fd0'
*** First throw call stack:
(
    0   CoreFoundation                      0x000000010934ec65 __exceptionPreprocess + 165
    1   libobjc.A.dylib                     0x000000010aeb9bb7 objc_exception_throw + 45
    2   CoreFoundation                      0x00000001093560ad -[NSObject(NSObject) doesNotRecognizeSelector:] + 205
    3   CoreFoundation                      0x00000001092ac13c ___forwarding___ + 988
    4   CoreFoundation                      0x00000001092abcd8 _CF_forwarding_prep_0 + 120
    5   UIKit                               0x0000000109beeda2 -[UIApplication sendAction:to:from:forEvent:] + 75
    6   UIKit                               0x0000000109d0054a -[UIControl _sendActionsForEvents:withEvent:] + 467
    7   UIKit                               0x0000000109cff919 -[UIControl touchesEnded:withEvent:] + 522
    8   UIKit                               0x0000000109c3b998 -[UIWindow _sendTouchesForEvent:] + 735
    9   UIKit                               0x0000000109c3c2c2 -[UIWindow sendEvent:] + 682
    10  UIKit                               0x0000000109c02581 -[UIApplication sendEvent:] + 246
    11  UIKit                               0x0000000109c0fd1c _UIApplicationHandleEventFromQueueEvent + 18265
    12  UIKit                               0x0000000109bea5dc _UIApplicationHandleEventQueue + 2066
    13  CoreFoundation                      0x0000000109282431 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
    14  CoreFoundation                      0x00000001092782fd __CFRunLoopDoSources0 + 269
    15  CoreFoundation                      0x0000000109277934 __CFRunLoopRun + 868
    16  CoreFoundation                      0x0000000109277366 CFRunLoopRunSpecific + 470
    17  GraphicsServices                    0x000000010d335a3e GSEventRunModal + 161
    18  UIKit                               0x0000000109bed900 UIApplicationMain + 1282
    19  Algorythm                           0x0000000109159157 main + 135
    20  libdyld.dylib                       0x000000010b611145 start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb)

can anyone help?, the program crashes in main, in the class AppDelegate

2 Answers

Donald White
Donald White
5,743 Points

I think you're missing self.view in the IBAction? It's trying to reference a selector on an object it's unable to recognize, in this case the view variable, but that doesn't exist as a global.

Josh Milbrandt
Josh Milbrandt
6,209 Points
Josh Milbrandt
Josh Milbrandt
6,209 Points

Thanks for the quick response, I got the code to work by using buttonPressed(sender: AnyObject)

however when I do things exactly like he does in the video I get the old error, is this maybe a change in Swift 1.2 or something?