如何從第一個組件選擇中加載UIPickerView的第二個組件中的數據

Question

我試圖爲我的問題找到一個解決方案一個多星期了，但沒有成功解決這個網站上的其他類似問題。

我有我的pickerView多個NSMutableArrays，我試圖根據第一個組件的選擇設置第二個組件的數據。我的主要問題是，當我選擇第一個組件中的第一個選項以外的任何其他組件時，第二個組件的數據是空的。當選擇第一個組件的第一個選項時，我的所有數組都依次排列在第二個組件中，但每個組件數據只需要一個數組。

這是我在ViewController.h代碼：

@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; 

這是我ViewController.m代碼：

@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]]; 
    } 
} 

當我的第一個組件選擇是首選「1型」在我的第二個組成部分我看到的NSMutableArray數據‘maListeSousTypes’和‘maListeSousTypes2’此起彼伏喜歡這裏： Screenshot

當從第一個組件中選擇「類型2」時，我的第二個組件是空的。

Answer 1

這必須比你正在做的更簡單。讓我告訴你我是如何在一個簡單的例子做了它：

@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 

，然後在您的實現：

@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 

隨意問，如果你不明白的東西。