iOS开发 UIPickerView的使用（2）两个选择器数据关联

在中介绍了UIPickerView的用法，当时选择的两组数据是没有任何关联的，可以任意组合，下面介绍限制的方法，就是第一个选择器的每个选项，都有不同的子选项。代码大部分与前文相似，只是实现了UIPickerViewDelegate协议中的-(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component方法，这个方法会在选择操作后触发，当用户在第一个选择器选择时，就会触发这个方法，我们在这个方法中重新载入第二个选择器的数据，即可。下面的代码与原教程有些不同，但思路是一样的。 viewController.h:

#import 

@interface BIDDependentComponentPickerViewController : UIViewController

@property (strong,nonatomic) NSArray * type1;
//存储第一个选择器的数据
@property (strong,nonatomic)NSArray * subtype;
//存储第二个选择器的数据，这个随着第一个选择器被选中的值而改变
@property (strong,nonatomic) NSArray * subtype1;
@property(strong,nonatomic)NSArray * subtype2;
@property (strong,nonatomic)NSArray * subtype3;
//上面三个用于存储第二个选择器的数据，根据第一个选择器选定的值，调用其中一个赋值给subtype
@property (strong, nonatomic) IBOutlet UIPickerView *dependentPicker;
- (IBAction)buttonPressed;

@end

viewController.m:

#import "BIDDependentComponentPickerViewController.h"

@implementation BIDDependentComponentPickerViewController
@synthesize dependentPicker;
@synthesize type1=_type1;
@synthesize subtype1=_subtype1;
@synthesize subtype2=_subtype2;
@synthesize subtype3=_subtype3;
@synthesize subtype=_subtype;

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)didReceiveMemoryWarning
{
    // Releases the view if it doesn't have a superview.
    [super didReceiveMemoryWarning];
    
    // Release any cached data, images, etc that aren't in use.
}

#pragma mark - View lifecycle

- (void)viewDidLoad
{
    [super viewDidLoad];
    NSArray *array=[NSArray arrayWithObjects:@"a",@"b",@"c", nil];
    _type1=array;
    NSArray *subarr1=[NSArray arrayWithObjects:@"aa",@"aaa",@"aaaa", nil];
    _subtype1=subarr1;
    NSArray *subarr2=[NSArray arrayWithObjects:@"bb",@"bbb",@"bbbb", nil];
    _subtype2=subarr2;
    NSArray *subarr3=[NSArray arrayWithObjects:@"cc",@"ccc",@"cccc", nil];
    _subtype3=subarr3;
    _subtype=subarr1;
    
    
    
    // Do any additional setup after loading the view from its nib.
}

- (void)viewDidUnload
{
    [self setDependentPicker:nil];
    _subtype1=nil;
    _subtype2=nil;
    _subtype3=nil;
    _type1=nil;
    _subtype=nil;
    [super viewDidUnload];
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    // Return YES for supported orientations
    return (interfaceOrientation == UIInterfaceOrientationPortrait);
}

- (IBAction)buttonPressed {
}

-(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
{
    return 2;
}
-(NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
{
    if (component==0) {
        return [_type1 count];
    }
    return [_subtype count];
}
-(NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
{
    if(component==0)
        return [_type1 objectAtIndex:row];
    
    return [_subtype objectAtIndex:row];
    
}
-(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
{
    if(component==0)
    {
        if (row==0) {
            _subtype=_subtype1;
        }else if(row==1)
        {
            _subtype=_subtype2;
        }else{
            _subtype=_subtype3;
        }
        
        [dependentPicker selectRow:0 inComponent:1 animated:YES];
        //使第二个选择器选中第一项，并且开启动画效果
        //如果没有上面这句，即便第一个选择器选项已经改变，第二个选择器的selectedRow还是不会变
        
        [dependentPicker reloadComponent:1];
        //重新载入第二个选择器
        
    }
    
    
}

@end