IOS学习之UIPickerView控件的关联选择

接上篇IOS学习之UIPickerView控件的简单使用

接着上篇的代码 http://download.csdn.net/detail/totogo2010/4391870 ，我们要实现的效果如下：



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：



最终代码：http://download.csdn.net/detail/totogo2010/4393004

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