两个UIPickerView控件间的数据依赖

         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, 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];    }

按钮事件设置

-(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];}

4.关于两个协议的代理方法

#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 *)pickerViewt didSelectRow:(NSInteger)row inComponent:(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；

附上源代码:http://download.csdn.net/detail/duxinfeng2010/4414456