Swift 中 UIPickerView 的自定义数据源类 [英] Custom data source class for UIPickerView in Swift
问题描述
我想像这样为 UIPickerView 创建一个单独的数据源类:
I wanted to create a separate data source class for UIPickerView like this:
class PickerData : NSObject, UIPickerViewDataSource {
// class definition goes here
var pickerDataSource = ["White", "Red", "Green", "Blue"];
func numberOfComponentsInPickerView(pickerView: UIPickerView) -> Int {
return 1
}
func pickerView(pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int {
return pickerDataSource.count;
}
func pickerView(pickerView: UIPickerView, titleForRow row: Int, forComponent component: Int) -> String! {
return pickerDataSource[row]
}
}
当我尝试使用它时,我得到 Thread 1: EXC_BAD_ACCESS ( code=1, address=0x0)
When I try to use it I get Thread 1: EXC_BAD_ACCESS ( code=1, address=0x0)
func createPickerView() -> UIView {
var picker = UIPickerView(frame:CGRectMake(20, 20, 480, 20))
picker.dataSource = PickerData();
picker.delegate = self;
var newView = UIView();
newView.setTranslatesAutoresizingMaskIntoConstraints(false);
newView.backgroundColor = UIColor.whiteColor();
newView.addSubview(picker)
self.view.addSubview(newView) // <-- ERROR HERE
return newView;
}
但是,如果我将 dataSource 更改为 self 它可以解决问题:
However, if I change the dataSource to self it fixes the problem:
picker.dataSource = self;
// and add the functions numberOfComponentsInPickerView etc to the
// main controller it works
但我不想使用 self
因为这将代码限制在一个页面上只有一个 UIPickerView.也许那还不错,但感觉有点悲伤的设计.
But I would not like to use self
because that limits the code to only one UIPickerView at one page. Maybe that's not so bad but it feels a bit sad design.
推荐答案
是的.我认为特罗是对的.最好将数据源对象设置为视图控制器上的变量.见下文(撰写本文时为 Swift 3):
Yep. I think Tero is right. It's best to have your data source object set as a variable on your view controller. See below (Swift 3 at time of writing):
import UIKit
class MyViewController: UIViewController, UIPickerViewDelegate {
var pickerDataSource = PickerData()
//...
// other properties, viewDidLoad, etc.
//...
func createPickerView() -> UIView {
var picker = UIPickerView(frame: CGRect(x: 20, y: 20, width: 480, height: 20))
picker.dataSource = pickerDataSource // Data source now set to member of MyViewController
picker.delegate = self
var newView = UIView()
newView.translatesAutoresizingMaskIntoConstraints = false
newView.backgroundColor = UIColor.white
newView.addSubview(picker)
self.view.addSubview(newView)
return newView
}
}
class PickerData: NSObject, UIPickerViewDataSource {
// Data source properties, initializer and methods here...
}
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