Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

iOS Build a Self-Destructing Message iPhone App Capturing Photo and Video Using UIImagePickerController viewDidLoad and the View Controller Lifecycle

Roderick Kar
Roderick Kar
8,456 Points
Posted by Roderick Kar
Roderick Kar
8,456 Points

cannot move to inbox of tabbar using imagePickerControllerDidCancel in Swift

i must have made mistakes trying to convert the code to swift. when running on an actual phone, i got into a situation where the camera keeps looping once i pressed "cancel". the lesson says setSelectedIndex to be applied to tabBarController but i could only find selectedIndex.

any help will be much appreciated.

thanks!

class CameraViewController: UITableViewController { var imagePicker = UIImagePickerController()

override func viewDidLoad() {
    super.viewDidLoad()
}

override func viewWillAppear(animated: Bool) {
    super.viewWillAppear(true)

    imagePicker.allowsEditing = false

    if UIImagePickerController.isSourceTypeAvailable(UIImagePickerControllerSourceType.Camera) {
        imagePicker.sourceType = UIImagePickerControllerSourceType.Camera
    }  else {
        imagePicker.sourceType = UIImagePickerControllerSourceType.PhotoLibrary
    }

    imagePicker.mediaTypes = UIImagePickerController.availableMediaTypesForSourceType(imagePicker.sourceType)!
    self.presentViewController(imagePicker, animated: false, completion: nil)
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
}

// MARK: - Table view data source

override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
    return 0
}

override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return 0
}

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCellWithIdentifier("cell", forIndexPath: indexPath) as UITableViewCell
    return cell
}
// MARK: - Image Picker Controller Delegate
func imagePickerControllerDidCancel(picker: UIImagePickerController!){
    self.dismissViewControllerAnimated(false, completion: nil)
    self.tabBarController?.selectedIndex = 0
}

}

1 Answer

Stone Preston
Stone Preston
42,016 Points
Stone Preston
Stone Preston
42,016 Points

its probably looping because of this line of code in viewWillAppear 

self.presentViewController(imagePicker, animated: false, completion: nil)

whenever you dismiss the imagePicker, the viewWillAppear method is called, resulting in the loop. maybe try setting the selectedIndex before dismissing the view controller

func imagePickerControllerDidCancel(picker: UIImagePickerController!){

    self.tabBarController!.selectedIndex = 0
    self.dismissViewControllerAnimated(false, completion: nil)

}
Roderick Kar
Roderick Kar
8,456 Points
Roderick Kar
Roderick Kar
8,456 Points

hi stone,

thanks for your quick response. i think it's looping because tab index 0 cannot be called up. focus of the app is supposed to switch from the camera tab to the inbox tab when the modal camera is cancelled. i just put a println() statement inside func imagePickerControllerDidCancel to see if the function get called at all. turns out it is never called. in face, if i comment out the whole func, the app behaves the same. so i think somehow the func code i wrote is never used. i just couldn't reconcile imagePickerControllerDidCancel with the objective-c code in the lesson completely. by the way, how do you mark the comment to make the codes appear inside a black box? i tried surrounding the code with ``` but it didn't work ...

code in the lesson:

  • (void) imagePickerControllerDidCancel:(UIImagePickerController *) picker { [self dismissViewControllerAnimated:NO completion:nil];

[self.tabBarController setSelectedIndex:0]; }

Stone Preston
Stone Preston
42,016 Points
Stone Preston
Stone Preston
42,016 Points

did you set your view controller as the image pickers delegate in viewDidLoad?

self.imagePickerController.delegate = self
Roderick Kar
Roderick Kar
8,456 Points
Roderick Kar
Roderick Kar
8,456 Points

cannot, imagePickerController not available, the only option available after typing self is ''' self.imagePicker.delegate = self ''' and it reports an error of "Type 'CameraViewController' does not conform to protocol 'UIImagePickerControllerDelegate'. btw, CameraViewController inherits from UITableViewController.

Stone Preston
Stone Preston
42,016 Points
Stone Preston
Stone Preston
42,016 Points

you need to add the UIImagePickerControllerDelegate protocol declaration to your class like so:

class CameraViewController : UITableViewController, UIImagePickerControllerDelegate
Roderick Kar
Roderick Kar
8,456 Points
Roderick Kar
Roderick Kar
8,456 Points

thank you for pointing me the right direction! i watched the lesson again and found there's an additional delegate needed, UINavigationControllerDelegate. also, i added self.imagePicker.delegate = self instead of self.imagePickerController.delegate = self. below is the working code:

class CameraViewController: UITableViewController, UIImagePickerControllerDelegate, UINavigationControllerDelegate {

var imagePicker = UIImagePickerController()

override func viewDidLoad() {
    super.viewDidLoad()
    self.imagePicker.delegate = self
}

override func viewWillAppear(animated: Bool) {
    super.viewWillAppear(true)

    imagePicker.allowsEditing = false

    if UIImagePickerController.isSourceTypeAvailable(UIImagePickerControllerSourceType.Camera) {
        imagePicker.sourceType = UIImagePickerControllerSourceType.Camera
    }  else {
        imagePicker.sourceType = UIImagePickerControllerSourceType.PhotoLibrary
    }

    imagePicker.mediaTypes = UIImagePickerController.availableMediaTypesForSourceType(imagePicker.sourceType)!
    self.presentViewController(imagePicker, animated: false, completion: nil)
}



// MARK: - Table view data source

override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
    return 0
}

override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    return 0
}

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCellWithIdentifier("cell", forIndexPath: indexPath) as UITableViewCell
    return cell
}

// MARK: - Image Picker Controller Delegate
func imagePickerControllerDidCancel(picker: UIImagePickerController) {
    println("imagePickerControl did cancel")
    self.tabBarController?.selectedIndex = 0
    self.dismissViewControllerAnimated(false, completion: nil)
}

}