如何从第一个组件选择中加载UIPickerView的第二个组件中的数据

Question

我试图为我的问题找到一个解决方案一个多星期了，但没有成功解决这个网站上的其他类似问题。

我有我的pickerView多个NSMutableArrays，我试图根据第一个组件的选择设置第二个组件的数据。我的主要问题是，当我选择第一个组件中的第一个选项以外的任何其他组件时，第二个组件的数据是空的。当选择第一个组件的第一个选项时，我的所有数组都依次排列在第二个组件中，但每个组件数据只需要一个数组。

这是我在ViewController.h代码：

@interface ViewController : UIViewController <UIPickerViewDataSource, UIPickerViewDelegate> 

{ 
    NSMutableArray *maListeTrier; 
    NSMutableArray *maListeTypes; 
    NSMutableArray *maListeSousTypes; 
    NSMutableArray *maListeSousTypes2; 
    NSMutableArray *maListeSousTypes3; 
    NSMutableArray *maListeSousTypes4; 
    NSMutableArray *maListeSousTypes5; 
} 

@property NSString *selectedType; 
@property NSString *selectedArray; 

@property (weak, nonatomic) IBOutlet UIPickerView *pickerView; 
@property (weak, nonatomic) IBOutlet UILabel *labelType; 
@property (weak, nonatomic) IBOutlet UILabel *labelSousType; 

这是我ViewController.m代码：

@synthesize selectedType; 
@synthesize selectedArray; 

- (void)viewDidLoad { 
    [super viewDidLoad]; 
    selectedType=[[NSString alloc]init]; 
    selectedArray=[[NSString alloc]init]; 

    maListeTypes = [[NSMutableArray alloc] init]; 
    [maListeTypes addObject:@"Type 1"]; 
    [maListeTypes addObject:@"Type 2"]; 

    maListeSousTypes=[[NSMutableArray alloc]init]; 
    [maListeSousTypes addObject:@"Sous-type 1"]; 
    [maListeSousTypes addObject:@"Sous-type 2"]; 
    [maListeSousTypes addObject:@"Sous-type 3"]; 
    [maListeSousTypes addObject:@"Sous-type 4"]; 
    [maListeSousTypes addObject:@"Sous-type 5"]; 

    maListeSousTypes2=[[NSMutableArray alloc]init]; 
    [maListeSousTypes addObject:@"22222"]; 
    [maListeSousTypes addObject:@"22222"]; 
    [maListeSousTypes addObject:@"22222"]; 
    [maListeSousTypes addObject:@"22222"]; 
    [maListeSousTypes addObject:@"22222"]; 
} 

- (void)didReceiveMemoryWarning { 
    [super didReceiveMemoryWarning]; 
    // Dispose of any resources that can be recreated. 
} 

//Méthode pour déterminer le nombre de colonnes dans chaque picker view 
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView { 
    return 2; 
} 

//Méthode pour déterminer le nombre de rangées dans chaque picker view 
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component { 
    if(component==0){ 
     return [maListeTypes count]; 
    } 
    else if(component==1){ 
     if([selectedType isEqualToString:@"Type 1"]){ 
      return [maListeSousTypes count]; 
     } 
     else if([selectedType isEqualToString:@"Type 2"]){ 
      return [maListeSousTypes2 count]; 
     } 
     else{ 
      return 0; 
     } 
    } 
    else{ 
     return 0; 
    } 
} 

//Méthode pour indiquer quoi afficher comme choix dans chaque picker view 
- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component { 
    if(component==0){ 
     return [maListeTypes objectAtIndex:row]; 
    } 
    else{ 
     if([selectedType isEqualToString:@"Type 1"]){ 
      return [maListeSousTypes objectAtIndex:row]; 
     } 
     else{ 
      return [maListeSousTypes2 objectAtIndex:row]; 
     } 
    } 
} 

//Méthode pour indiquer quelle action va se produire lorsqu'on clique sur un des choix des picker views 
-(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component{ 
    if(component==0){ 
     selectedType=[maListeTypes objectAtIndex:row]; 
     [pickerView reloadAllComponents]; 
     _labelType.text=[maListeTypes objectAtIndex:[pickerView selectedRowInComponent:0]]; 
    } 
    else if(component==1){ 
     _labelSousType.text=[maListeSousTypes objectAtIndex:[pickerView selectedRowInComponent:1]]; 
    } 
} 

当我的第一个组件选择是首选“1型”在我的第二个组成部分我看到的NSMutableArray数据‘maListeSousTypes’和‘maListeSousTypes2’此起彼伏喜欢这里： Screenshot

当从第一个组件中选择“类型2”时，我的第二个组件是空的。

Answer 1

这必须比你正在做的更简单。让我告诉你我是如何在一个简单的例子做了它：

@interface ViewController() <UIPickerViewDataSource, UIPickerViewDelegate> 

@property (strong, nonatomic) IBOutlet UIPickerView *pickerView; 

@property (nonatomic, strong) NSArray *leftComponentItems; // Items from this array will populate the left component 
@property (nonatomic, strong) NSArray *rightComponentItemsA; // Items from this array will populate the right component, when the 1st row of the left component is selected 
@property (nonatomic, strong) NSArray *rightComponentItemsB; // Items from this array will populate the right component, when the 2nd row of the left component is selected 

@property (nonatomic, assign) NSInteger selectedLeftRow; // This keeps track of the selected row on the left component (you could take that from the datasource as well) 

@end 

，然后在您的实现：

@implementation ViewController 

- (void)viewDidLoad { 
    [super viewDidLoad]; 

    self.selectedLeftRow = 0; 

    self.leftComponentItems = @[@"first", @"second"]; 

    self.rightComponentItemsA = @[@"A1", @"A2", @"A3", @"A4", @"A5"]; 
    self.rightComponentItemsB = @[@"B1", @"B2", @"B3", @"B4", @"B5", @"B6", @"B7"]; 
} 

-(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView { 
    return 2; // We have left & right components, this will always be "2" 
} 

-(NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component { 
    if (component == 0) { 
     return self.leftComponentItems.count; 
    } 

    if (component == 1) { 
     if (self.selectedLeftRow == 0) { 
      return self.rightComponentItemsA.count; 
     } else { 
      return self.rightComponentItemsB.count; 
     } 
    } 

    return 0; 
} 

-(NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component { 

    if (component == 0) { 
     return self.leftComponentItems[row]; 
    } 

    if (component == 1) { 
     if (self.selectedLeftRow == 0) { 
      return self.rightComponentItemsA[row]; 
     } else { 
      return self.rightComponentItemsB[row]; 
     } 
    } 

    return @"default"; 

} 

-(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component { 
    if (component == 0) { 
     self.selectedLeftRow = row; // We keep track of the selected row 
     [pickerView reloadComponent:1]; // When we select a row in the left component, update the data on the right component 
    } 
} 

@end 

随意问，如果你不明白的东西。