Swift-选择框（UIPickerView）的用法

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原作者: [db:作者] 来自: [db:来源] 收藏邀请

1，选择框可以让用户以滑动的方式选择值。示例如下：

import UIKit
 
class ViewController:UIViewController, UIPickerViewDelegate, UIPickerViewDataSource{

    var pickerView:UIPickerView!

    override func viewDidLoad() {

        super.viewDidLoad()

        pickerView=UIPickerView()

        //将dataSource设置成自己

        pickerView.dataSource=self

        //将delegate设置成自己

        pickerView.delegate=self

        //设置选择框的默认值

        pickerView.selectRow(1,inComponent:0,animated:true)

        pickerView.selectRow(2,inComponent:1,animated:true)

        pickerView.selectRow(3,inComponent:2,animated:true)

        self.view.addSubview(pickerView)

        //建立一个按钮，触摸按钮时获得选择框被选择的索引

        var button=UIButton(frame:CGRectMake(0,0,100,30))

        button.center=self.view.center

        button.backgroundColor=UIColor.blueColor()

        button.setTitle("获取信息",forState:.Normal)

        button.addTarget(self, action:"getPickerViewValue",

            forControlEvents: UIControlEvents.TouchUpInside)

        self.view.addSubview(button)

    }

    //设置选择框的列数为3列,继承于UIPickerViewDataSource协议

    func numberOfComponentsInPickerView( pickerView: UIPickerView) -> Int{

        return 3

    }

    //设置选择框的行数为9行，继承于UIPickerViewDataSource协议

    func pickerView(pickerView: UIPickerView,numberOfRowsInComponent component: Int) -> Int{

        return 9

    }

    //设置选择框各选项的内容，继承于UIPickerViewDelegate协议

    func pickerView(pickerView:UIPickerView!,titleForRow row: Int,forComponent component: Int)

        -> String!{

        return String(row)+"-"+String(component)

    }

    //触摸按钮时，获得被选中的索引

    func getPickerViewValue(){

        var alertView=UIAlertView();

        alertView.title="被选中的索引为"

        alertView.message=String(pickerView.selectedRowInComponent(0))+"-"+String(pickerView!.selectedRowInComponent(1))+"-"+String(pickerView.selectedRowInComponent(2))

        alertView.addButtonWithTitle("OK")

        alertView.show()

    }
}

2，调整选择框的尺寸
UIPickerView用frame和center两个属性设置整个选择框的大小和位置。
如果要调整内部列的宽度，需要实现UIPickerViewDelegate协议类中pickerView:widthForComponent方法设置
如果要调整内部行高，则需要实习上述协议类中pickerView:rowHeightForComponent方法设置

//设置列宽

func pickerView(pickerView: UIPickerView！,widthForComponent component: Int) -> CGFloat{

    if(00 == component){

        //第一列变宽

        return 100

    }else{

        //第二、三列变窄

        return 30

    }
}
 
//设置行高

func pickerView(pickerView: UIPickerView！,rowHeightForComponent component: Int) -> CGFloat{

    return 50
}

3，将图片作为选择框选项
选择框选项的内容，除了可以使字符串类型的，还可以是任意UIView类型的元素。比如我们将选项内容设置为图片：

func pickerView(pickerView:UIPickerView!,viewForRow row: Int,forComponent component: Int,

 reusingView view:UIView!) -> UIView!{

    var image = UIImage(named:"icon_"+String(row))

    var imageView = UIImageView()

    imageView.image = image

    return imageView
}

4，检测响应选项的选择状态

func pickerView(pickerView: UIPickerView！,didSelectRow row: Int, inComponent component: Int){

    //将在滑动停止后触发，并打印出选中列和行索引

    println(component)

    println(row)
}