UIPickerView控件的关联选择（二）

接上篇iOS学习之UIPickerView控件的简单使用 （一）

我们要实现的效果如下：
1[img]

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当选择左边的一级选项时，左边展示一级选项里含有的二级选项，选择后显示在TextField里。

如何实现呢？建立一个和左边的列表key对应的数组，当选择这个key时，刷新左边UIPickerView部分的内容显示对应数组的数据，选择时，找到

两个UIPickerView部件rowIndex，找出数据，放到TextField里。


1、打开上篇PickerViewDemo项目，在ViewController.h添加两个成员变量：NSArray *subPickerArray; NSDictionary *dicPicker;

#import <UIKit/UIKit.h>

@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：

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