@interface ViewController : UIViewController<UIPickerViewDelegate, UITextFieldDelegate,UIPickerViewDataSource>{    NSArray *pickerArray;    NSArray *subPickerArray;    NSDictionary *dicPicker;}- (IBAction)selectButton:(id)sender;@property (strong, nonatomic) IBOutlet UIToolbar *doneToolbar;@property (strong, nonatomic) IBOutlet UIPickerView *selectPicker;@property (strong, nonatomic) IBOutlet UITextField *textField;@end

2、初始化

- (void)viewDidLoad{    [super viewDidLoad];    pickerArray = [NSArray arrayWithObjects:@"动物",@"植物",@"石头", nil];    dicPicker = [NSDictionary dictionaryWithObjectsAndKeys:                 [NSArray arrayWithObjects:@"鱼",@"鸟",@"虫子",            nil], @"动物",                 [NSArray arrayWithObjects:@"花",@"草",@"葵花",            nil], @"植物",                 [NSArray arrayWithObjects:@"疯狂的石头",@"花岗岩",@"鹅卵石", nil], @"石头",nil];        subPickerArray = [dicPicker objectForKey:@"动物"];    textField.inputView = selectPicker;    textField.inputAccessoryView = doneToolbar;    textField.delegate = self;    selectPicker.delegate = self;    selectPicker.dataSource = self;    selectPicker.frame = CGRectMake(0, 480, 320, 216);}

给 NSDictionary *dicPicker;赋值，对应的三个关键字添加了对应的数组。

3、Component返回两个，这样就有两个齿轮了。

-(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView{    return 2;}

4、使用宏

在#import "ViewController.h"下面定义两个宏，代表UIPickerView齿轮的左边的部分和右边的部分。左边的部分是0，右边的是1.

#import "ViewController.h"

#define kFirstComponent 0

#define kSubComponent 1

5、判断是那个齿轮，返回相应的数据的Count。

-(NSInteger) pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component{    if(component == kFirstComponent){        return [pickerArray count];    }else {        return [subPickerArray count];    }}

6、根据component返回相应的String数据

    -(NSString*) pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component{    if(component == kFirstComponent){        return [pickerArray objectAtIndex:row];    }else {        return [subPickerArray objectAtIndex:row];    }}

7、拖动左边的齿轮时，右边的数据相应的Reload更新。

-(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component{    if (component == kFirstComponent) {        subPickerArray = [dicPicker objectForKey:[pickerArray objectAtIndex:row]];         [pickerView selectRow:0 inComponent:kSubComponent animated:YES];        [pickerView reloadComponent:kSubComponent];    }}

8、相应选择的数据，并显示在TextField上。

-(void)textFieldDidEndEditing:(UITextField *)textField{    NSInteger firstViewRow = [selectPicker selectedRowInComponent:kFirstComponent];    NSInteger subViewRow = [selectPicker selectedRowInComponent:kSubComponent];    NSString * firstString = [pickerArray objectAtIndex:firstViewRow];    NSString * subString =  [[dicPicker objectForKey:[pickerArray objectAtIndex:firstViewRow]] objectAtIndex:subViewRow] ;    NSString *textString = [[NSString alloc ] initWithFormat:@"您选择了：%@%@%@", firstString, @" 里的 ", subString];    self.textField.text = textString;}- (IBAction)selectButton:(id)sender {    [textField endEditing:YES];}

大功告成，运行，点击TextField，弹出：

UIViewController 总结