1. 基本概念

UIPickerView是一个常用的IOS控件，在选择日期和时间时很常用。

屏幕快照 2016-12-05 下午8.02.06.png

UIPickerView主要有以下内容：

屏幕快照 2016-12-05 下午8.03.56.png

2. 创建方法

先去视图控制器ViewController.m的ViewDidLoad中添加：

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo}p.p2 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo; color: #3d1d81}p.p3 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo; color: #008400}p.p4 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo; min-height: 13.0px}p.p5 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px 'Heiti SC Light'; color: #008400}p.p6 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo; color: #703daa}span.s1 {font-variant-ligatures: no-common-ligatures}span.s2 {font-variant-ligatures: no-common-ligatures; color: #bb2ca2}span.s3 {font-variant-ligatures: no-common-ligatures; color: #000000}span.s4 {font: 11.0px Menlo; font-variant-ligatures: no-common-ligatures; color: #000000}span.s5 {font: 11.0px Menlo; font-variant-ligatures: no-common-ligatures}span.s6 {font-variant-ligatures: no-common-ligatures; color: #3d1d81}span.s7 {font-variant-ligatures: no-common-ligatures; color: #703daa}span.s8 {font-variant-ligatures: no-common-ligatures; color: #272ad8}

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    
    
    //创建选择视图对象
    //用来显示多组数据和多个元素以供选择
    UIPickerView* pickerView=[[UIPickerView alloc]init];
    pickerView.frame=CGRectMake(10, 100, 300, 200);
    //设置普通代理对象为当前的视图控制器
    pickerView.delegate=self;
    //设置数据代理对象为当前视图控制器
    pickerView.dataSource=self;
    
    [self.view addSubview:pickerView];
}

此时显示warning，因为ViewController没有继承相关协议，所以去ViewController.h中继承：

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo; color: #d12f1b}p.p2 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo; min-height: 13.0px}p.p3 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo}p.p4 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px 'Heiti SC Light'; color: #008400}p.p5 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo; color: #703daa}p.p6 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo; color: #bb2ca2}span.s1 {font-variant-ligatures: no-common-ligatures; color: #78492a}span.s2 {font-variant-ligatures: no-common-ligatures}span.s3 {font-variant-ligatures: no-common-ligatures; color: #bb2ca2}span.s4 {font-variant-ligatures: no-common-ligatures; color: #703daa}span.s5 {font: 11.0px Menlo; font-variant-ligatures: no-common-ligatures}span.s6 {font-variant-ligatures: no-common-ligatures; color: #000000}

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController

//继承协议
//普通协议：处理视图选取等事件
//数据协议：处理获取数据时的代理协议函数
<UIPickerViewDataSource, UIPickerViewDelegate>

@end

此时尝试运行程序，程序崩溃，因为还没有实现相关协议函数。

3. 协议函数

• 设置行列数和显示内容：

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo; min-height: 13.0px}p.p2 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px 'Heiti SC Light'; color: #008400}p.p3 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo}p.p4 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo; color: #008400}p.p5 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo; color: #3d1d81}span.s1 {font-variant-ligatures: no-common-ligatures}span.s2 {font: 11.0px Menlo; font-variant-ligatures: no-common-ligatures}span.s3 {font-variant-ligatures: no-common-ligatures; color: #703daa}span.s4 {font-variant-ligatures: no-common-ligatures; color: #000000}span.s5 {font: 11.0px 'Heiti SC Light'; font-variant-ligatures: no-common-ligatures}span.s6 {font-variant-ligatures: no-common-ligatures; color: #bb2ca2}span.s7 {font-variant-ligatures: no-common-ligatures; color: #272ad8}span.s8 {font-variant-ligatures: no-common-ligatures; color: #3d1d81}span.s9 {font-variant-ligatures: no-common-ligatures; color: #d12f1b}span.s10 {font: 11.0px 'Heiti SC Light'; font-variant-ligatures: no-common-ligatures; color: #d12f1b}

//实现获取数组的协议函数
//返回值为选择视图的组数
//整数类型
-(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
{
    //返回3组
    return 3;
}

//实现每组元素的个数
//每组元素有多少行
-(NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
{
    if (component==0) {
        return 3;
    }
    else if (component==1)
    {
        return 5;
    }
    else
        return 10;
}

//显示每个元素的内容
-(NSString*)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
{
    NSString* str=[NSString stringWithFormat:@"%d组%d行",component+1,row+1];
    return str;
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

//设置每列宽度
-(CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component
{
    if (component==0) {
        return 50;
    }
    return 80;
}

• 返回所选的行数的index

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px 'Heiti SC Light'; color: #008400}p.p2 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo}p.p3 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo; min-height: 13.0px}span.s1 {font: 11.0px Menlo; font-variant-ligatures: no-common-ligatures}span.s2 {font-variant-ligatures: no-common-ligatures}span.s3 {font-variant-ligatures: no-common-ligatures; color: #bb2ca2}span.s4 {font-variant-ligatures: no-common-ligatures; color: #703daa}span.s5 {font-variant-ligatures: no-common-ligatures; color: #272ad8}span.s6 {font-variant-ligatures: no-common-ligatures; color: #3d1d81}span.s7 {font-variant-ligatures: no-common-ligatures; color: #d12f1b}span.s8 {font: 11.0px 'Heiti SC Light'; font-variant-ligatures: no-common-ligatures; color: #d12f1b}

//返回选中的行
-(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
{
    if (component==0) {
        NSLog(@"第一列选中第%ld个",row+1);
    }
    if (component==1) {
        NSLog(@"第二列选中第%ld个",row+1);
    }
    if (component==2) {
        NSLog(@"第三列选中第%ld个",row+1);
    }
    
}

• 添加图片视图(类似老虎机游戏)

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px 'Heiti SC Light'; color: #008400}p.p2 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.0px Menlo; color: #008400}span.s1 {font: 11.0px Menlo; font-variant-ligatures: no-common-ligatures}span.s2 {font-variant-ligatures: no-common-ligatures}

//可以将自定义的视图显示到屏幕上
//-(UIView*)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view
//{
//   UIImage* image=[UIImage imageNamed:[NSString stringWithFormat:@"%ld.jpg",row%7+1]];
//   UIImageView* iView=[[UIImageView alloc]initWithImage:image];
//    
//    return iView;
//    
//}