ios - 选择器越界异常

Question

我的类项目遇到了一些困难。我需要使用带有两个组件的选择器创建一个 View 。当我选择第一个组件中的行时，它需要更新第二个组件的选项。我的问题是，同时移动两个组件时出现越界异常。有什么建议吗？

slider 的代码会随着选择器的更新而更新，反之亦然。我的代码是:

import UIKit
 class FirstViewController: UIViewController, UIPickerViewDataSource, UIPickerViewDelegate {
@IBOutlet weak var FoodPicker: UIPickerView!
@IBOutlet weak var FoodSlider: UISlider!

let Countries = ["India","USA","Mexico"]
let IndianFood = ["Avakaya","Pesarattu","Thukpa","Thali","Litti Chokha","Maple","Palak Paneer","Rajma-Shawl","Vindaloo","Khaman","Handva","Bisi bele bath","Pav Bhaji","Eromba","Chungdi Jhola"]
let USFood = ["Hot Dog","Pizza","Hamburger","Clam Chowder","Succotash","Fried Chicken","Gumbo","Grits","Chitterlings","Hushpuppies","Cobbler"]
let MexicanFood = ["Taco","Quesadilla","Pambazo","tamal","huarache","Alambre","Enchilada","Panita","Gordita","Tlayuda","Sincronizada"]

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
    FoodPicker.dataSource = self
    FoodPicker.delegate = self
}

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

//MARK: - Picker Creation
// returns the number of 'columns' to display.
public func numberOfComponents(in pickerView: UIPickerView) -> Int {
    return 2
}

// returns the # of rows in each component..
public func pickerView(_ pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
    switch component {
    case 1:
        switch FoodPicker.selectedRow(inComponent: 0) {
        case 1:
            return USFood.count
        case 2:
            return MexicanFood.count
        default:
            return IndianFood.count
        }
    default:
        return Countries.count
    }
}

//MARK: - Picker Delegate
//returns picker row names
func pickerView(_ pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String? {
    switch component {
    case 1:
        switch FoodPicker.selectedRow(inComponent: 0) {
        case 1:
            return USFood[row]
        case 2:
            return MexicanFood[row]
        default:
            return IndianFood[row]
        }
    default:
        return Countries[row]
    }
}

//MARK: - Picker Updater
func pickerView(_ pickerView: UIPickerView, didSelectRow row: Int, inComponent component: Int) {
    if 0==component {
        FoodPicker.reloadComponent(1)
        switch row {
        case 1:
            FoodSlider.maximumValue = Float(USFood.count-1)
        case 2:
            FoodSlider.maximumValue = Float(MexicanFood.count-1)
        default:
            FoodSlider.maximumValue = Float(IndianFood.count-1)
        }
    }
    if 1==component {
        FoodSlider.setValue(Float(row), animated: true)
    }
}

@IBAction func sliderSelector(_ sender: AnyObject) {
    FoodPicker.selectRow(Int(FoodSlider.value), inComponent: 1, animated: true)
}
}

出现的错误是:

2016-10-26 21:21:15.943915 assignment4[10836:5039575] subsystem: com.apple.UIKit, category: Feedback, enable_level: 1, persist_level: 0, default_ttl: 0, info_ttl: 0, debug_ttl: 0, generate_symptoms: 0, enable_oversize: 1, privacy_setting: 2, enable_private_data: 0
fatal error: Index out of range
(lldb) 

Answer 1

我假设崩溃的原因发生在下面一行

@IBAction func sliderSelector(_ sender: AnyObject) {
    FoodPicker.selectRow(Int(FoodSlider.value), inComponent: 1, animated: true)
}

如果您在上面的行中设置大于 2(范围从 0)的 int 值。那么你会得到上面的错误。因为选择器的组件1只有计数为3的数组