[UIActivityIndicatorView release]: message sent to deallocated instance in swift-3

Question

I'm using an activity indicator in mine api calling mechanism, while hiding the HUD the code gets crash and shooting an error of "[UIActivityIndicatorView release]: message sent to deallocated instance".

Here is stack:

 * thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BREAKPOINT (code=1, subcode=0x18a5e6ea8)
  * frame #0: 0x000000018a5e6ea8 CoreFoundation`___forwarding___ + 744
    frame #1: 0x000000018a4e2d4c CoreFoundation`_CF_forwarding_prep_0 + 92
    frame #2: 0x000000018a4c2a80 CoreFoundation`-[__NSArrayI dealloc] + 84
    frame #3: 0x0000000189062134 libobjc.A.dylib`(anonymous namespace)::AutoreleasePoolPage::pop(void*) + 836
    frame #4: 0x0000000190711c3c UIKit`-[UIView dealloc] + 1604
    frame #5: 0x0000000189062134 libobjc.A.dylib`(anonymous namespace)::AutoreleasePoolPage::pop(void*) + 836
    frame #6: 0x000000018a4beb28 CoreFoundation`_CFAutoreleasePoolPop + 28
    frame #7: 0x000000018a58ecec CoreFoundation`__CFRunLoopRun + 1580
    frame #8: 0x000000018a4beda4 CoreFoundation`CFRunLoopRunSpecific + 424
    frame #9: 0x000000018bf28074 GraphicsServices`GSEventRunModal + 100
    frame #10: 0x0000000190779058 UIKit`UIApplicationMain + 208
    frame #11: 0x0000000100147448 GraspIO-Dev`main at AppDelegate.swift:14
    frame #12: 0x00000001894cd59c libdyld.dylib`start + 4

I couldn't get what's the mistake I'm making and here is mine show and hide code.

func execute( _ params : String..., serverResponse: @escaping (ServerResponseModel) -> Void) {
        //print("params:\(params)");

        if self.mCallingView != nil {
            DispatchQueue.main.async{
                self.showLoadingHUD()
            }
          }
        }

        makeWebServiceCall(params){
            response in
            //print("\n\n response: \(response)")
            DispatchQueue.main.async { 
                 serverResponse(response!)
                if self.mCallingView != nil {
                  self.hideLoadingHUD()   
                }
            }
        }
    }

    fileprivate func showLoadingHUD() {
        let hud = MBProgressHUD.showAdded(to: mCallingView!, animated: true)
        hud.label.text = "Please wait..."
    }

    fileprivate func hideLoadingHUD() {
        let _ = MBProgressHUD.hide(for: mCallingView!, animated: true)
        mCallingView!.isUserInteractionEnabled = true
        mCallingView = nil
    }

The app will crash on while hiding the HUD,Did a research in stack overflow but couldn't found a solution for it.

Answer 1

The error is quite descriptive. You are trying to set something nil that has already been release. Now you need to find the place where you are doing it and a way to avoid this. As you mentioned you are getting this while hiding it. So you have already zeroed on the issue.

fileprivate func hideLoadingHUD() {
    let _ = MBProgressHUD.hide(for: mCallingView!, animated: true)
    mCallingView!.isUserInteractionEnabled = true
    mCallingView = nil
}

Here. You are trying to to make mCallingView = nil. Remove this line and check if you get the error. Do you really need to make the source view nil, while hiding the activity indicator?