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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

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

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

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?