我正在构建一个非常简单的 swift 应用程序，它使用两个视图控制器——“ViewControler”和“AnimalChooserViewControler”。第一个有一个简单的标签和一个带有一个项目的工具栏，它将用户转移到第二个屏幕。第二，有自定义选择器。该应用程序的全部目的是使用输出 UILabel 显示用户从第二个视图控制器到第一个视图控制器中选择的任何内容。我不得不提到我正在使用 xCode 6.4 (ios8)
我的问题是当我尝试将presentedViewController 转换为！ViewController 应用程序因“致命错误：在展开可选值 (lldb) 时意外发现 nil”异常而崩溃。如何解决这个问题，有什么建议吗？这是我在 ViewControler 中的代码：
class ViewController: UIViewController {
@IBOutlet weak var outputLabel: UILabel!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func displayAnimal(choosenAnimal: String, withSound choosenSound: String, fromComponent choosenComponent: String){
self.outputLabel.text = "You changed \(choosenComponent) (\(choosenAnimal)(and the sound \(choosenSound))"
}
}
这是我在 AnimalChooserViewControler 中的代码
class AnimalChooserViewController: UIViewController, UIPickerViewDataSource, UIPickerViewDelegate{
let kComponentCount: Int = 2
let kAnimalComponent: Int = 0
let kSoundComponent: Int = 1
var animalNames: [String] = []
var animalSounds: [String] = []
var animalImages: [UIImageView] = []
@IBAction func dismisAnimalChooser(sender: AnyObject) {
dismissViewControllerAnimated(true, completion: nil)
}
func numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int {
return kComponentCount
}
func pickerView(pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
if component == kAnimalComponent{
return animalNames.count
} else {
return animalSounds.count
}
}
func pickerView(pickerView: UIPickerView, viewForRow row: Int, forComponent component: Int, reusingView view: UIView!) -> UIView {
if component == kAnimalComponent {
let choosenImageView: UIImageView = animalImages[row]
let workarroundImageView: UIImageView = UIImageView(frame: choosenImageView.frame)
workarroundImageView.backgroundColor = UIColor(patternImage: choosenImageView.image!)
return workarroundImageView
} else {
let soundLabel: UILabel = UILabel(frame: CGRectMake(0, 0, 100, 32))
soundLabel.text = animalSounds[row]
return soundLabel
}
}
func pickerView(pickerView: UIPickerView, rowHeightForComponent component: Int) -> CGFloat {
return 55.0
}
func pickerView(pickerView: UIPickerView, widthForComponent component: Int) -> CGFloat {
if component == kAnimalComponent{
return 75.0
} else {
return 150.0
}
}
func pickerView(pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
let initialView : ViewController = presentedViewController as! ViewController
if component == kAnimalComponent{
let choosenSound: Int = pickerView.selectedRowInComponent(self.kSoundComponent)
initialView.displayAnimal(animalNames[row], withSound: animalSounds[choosenSound], fromComponent: "the Animal")
} else {
let choosenAnimal: Int = pickerView.selectedRowInComponent(kAnimalComponent)
initialView.displayAnimal(animalNames[choosenAnimal], withSound: animalSounds[row], fromComponent: "the Sound")
}
}
override func viewDidLoad() {
super.viewDidLoad()
animalNames = ["Mouse","Goose","Cat","Dog","Snake","Bear","Pig"]
animalSounds = ["Oink","Rawr","Sss","Meow","Honk","Squeak"]
animalImages = [UIImageView(image: UIImage(named: "mouse.png")),
UIImageView(image: UIImage(named: "goose.png")),
UIImageView(image: UIImage(named: "cat.png")),
UIImageView(image: UIImage(named: "dog.png")),
UIImageView(image: UIImage(named: "snake.png")),
UIImageView(image: UIImage(named: "bear.png")),
UIImageView(image: UIImage(named: "pig.png"))]
preferredContentSize = CGSizeMake(340,380)
}
override func viewDidAppear(animated: Bool) {
super.viewDidAppear(animated)
let initialView: ViewController = presentedViewController as! ViewController
initialView.displayAnimal(animalNames[0], withSound: animalSounds[0], fromComponent: "nothing yet...")
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
/*
// MARK: - Navigation
// In a storyboard-based application, you will often want to do a little preparation before navigation
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
// Get the new view controller using segue.destinationViewController.
// Pass the selected object to the new view controller.
}
*/
}