本篇实现功能是两个选取器的关联操作，滚动第一个滚轮第二个滚轮内容随着第一个的变化而变化，然后点击按钮触发一个动作；工程是在 代码实现UIPickerView 一文中基础上修改的，建工程就不多说，先把效果图贴出来:

1.首先在工程中建一个songInfo.plist文件，储存数据，

添加的内容是：

2.在ViewController定一个选取器pickerView对象，两个数组，存放选取器数据和一个字典，读取plist文件

#import <UIKit/UIKit.h>  @interface ViewController : UIViewController<UIPickerViewDelegate,UIPickerViewDataSource> { //定义滑轮组建     UIPickerView *pickerView; //    储存第一个选取器的的数据     NSArray *singerData; //    储存第二个选取器     NSArray *singData; //    读取plist文件数据     NSDictionary *pickerDictionary;  }  -(void) buttonPressed:(id)sender;  @end

3.在ViewController.m文件中ViewDidLoad完成初始化

首先定义两个宏定义，分别表示两个选取器的索引序号值，放在 #import"ViewController.h"后面

#define singerPickerView 0

#define singPickerView 1

- (void)viewDidLoad {     [super viewDidLoad]; 	// Do any additional setup after loading the view,typically from a nib.          pickerView = [[UIPickerView alloc] initWithFrame:CGRectMake(0,320,216)]; //    指定Delegate     pickerView.delegate=self;     pickerView.dataSource=self; //    显示选中框     pickerView.showsSelectionIndicator=YES;     [self.view addSubview:pickerView];  //    获取mainBundle     NSBundle *bundle = [NSBundle mainBundle]; //    获取songInfo.plist文件路径     NSURL *songInfo = [bundle URLForResource:@"songInfo" withExtension:@"plist"]; //    把plist文件里内容存入数组     NSDictionary *dic = [NSDictionary dictionaryWithContentsOfURL:songInfo];     pickerDictionary=dic; //    将字典里面的内容取出放到数组中     NSArray *components = [pickerDictionary allKeys];  //选取出第一个滚轮中的值         NSArray *sorted = [components sortedArrayUsingSelector:@selector(compare:)];          singerData = sorted;      //    根据第一个滚轮中的值，选取第二个滚轮中的值     NSString *selectedState = [singerData objectAtIndex:0];     NSArray *array = [pickerDictionary objectForKey:selectedState];     singData=array;               //     添加按钮        CGRect frame = CGRectMake(120,250,80,40);     UIButton *selectButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];     selectButton.frame=frame;     [selectButton setTitle:@"SELECT" forState:UIControlStateNormal];          [selectButton addTarget:self action:@selector(buttonPressed:) forControlEvents:UIControlEventTouchUpInside];          [self.view addSubview:selectButton];      } 

-(void) buttonPressed:(id)sender { //    获取选取器某一行索引值      NSInteger singerrow =[pickerView selectedRowInComponent:singerPickerView];      NSInteger singrow = [pickerView selectedRowInComponent:singPickerView]; //   将singerData数组中值取出       NSString *selectedsinger = [singerData objectAtIndex:singerrow];      NSString *selectedsing = [singData objectAtIndex:singrow];      NSString *message = [[NSString alloc] initWithFormat:@"你选择了%@的%@",selectedsinger,selectedsing];          UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"提示"                                                      message:message                                                    delegate:self                                           cancelButtonTitle:@"OK"                                           otherButtonTitles: nil];     [alert show];  }

#pragma mark - #pragma mark Picker Date Source Methods  //返回显示的列数 -(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView { //    返回几就有几个选取器     return 2; } //返回当前列显示的行数 -(NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component {       if (component==singerPickerView) {         return [singerData count];     }              return [singData count];      }

#pragma mark Picker Delegate Methods  //返回当前行的内容,此处是将数组中数值添加到滚动的那个显示栏上 -(NSString*)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component {     if (component==singerPickerView) {         return [singerData objectAtIndex:row];     }              return [singData objectAtIndex:row];           }

-(void)pickerView:(UIPickerView *)pickerViewt didSelectRow:(NSInteger)row inComponent:(NSInteger)component { //    如果选取的是第一个选取器     if (component == singerPickerView) { //        得到第一个选取器的当前行         NSString *selectedState =[singerData objectAtIndex:row];          //        根据从pickerDictionary字典中取出的值，选择对应第二个中的值         NSArray *array = [pickerDictionary objectForKey:selectedState];         singData=array;         [pickerView selectRow:0 inComponent:singPickerView animated:YES];                   //        重新装载第二个滚轮中的值         [pickerView reloadComponent:singPickerView];     } }

//设置滚轮的宽度 -(CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component {     if (component == singerPickerView) {         return 120;     }     return 200; } 

在这个方法中，-(void)pickerView:(UIPickerView*)pickerViewtdidSelectRow:(NSInteger)rowinComponent:(NSInteger)component ，我把(UIPickerView*)pickerView参数改成了(UIPickerView*)pickerViewt，因为我定义的pickerView对象和参数发生冲突，所以把参数给改了下；