obj-c : iphone编程pickerview titleforrow方法问题

Question

我有一个包含 2 个组件的 pickerView，当我选择组件 1 中的第 1 行时，它会将一个数组列表加载到组件 2 中。如果我选​​择组件 1 中的第 2 行，它将加载另一个数组列表组件2.有可能吗？

- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {


 return 2; 



}





- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component {

 if (component == 0){
  return [arraylist1 count];
 if (component == 1) {
  if ([pickerViewcustom selectedRowInComponent:0] == 0) {
   return [arraylist3 count];
  }
 }
 }




 return 0;

}

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




 if (component == 0){
   return [arraylist1 objectAtIndex:row];
  if (component == 1) {
   if ([pickerViewcustom selectedRowInComponent:0] == 0) {
    return [arraylist3 objectAtIndex:row];
   }
  }

 }

 return 0;

}




- (CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component {



    return 150;
}
- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
{




 [pickerViewcustom reloadComponent:0];
 [pickerViewcustom reloadComponent:1];













}

Answer 1

尝试这样的事情：

#import <UIKit/UIKit.h>

#define kStateComponent 0
#define kZipComponent 1

@interface DependentComponentPickerViewController : UIViewController  <UIPickerViewDelegate, UIPickerViewDataSource> {
    IBOutlet UIPickerView *picker;
    NSDictionary *stateZips;
    NSArray *states;
    NSArray *zips;
}
@property (retain, nonatomic) UIPickerView *picker;
@property (retain, nonatomic) NSDictionary *stateZips;
@property (retain, nonatomic) NSArray *states;
@property (retain, nonatomic) NSArray *zips;
- (IBAction)butonPressed:(id)sender;
@end

#import "DependentComponentPickerViewController.h"

@implementation DependentComponentPickerViewController
@synthesize picker;
@synthesize stateZips;
@synthesize states;
@synthesize zips;

- (IBAction)butonPressed:(id)sender
{
    NSInteger stateRow = [picker selectedRowInComponent:kStateComponent];
    NSInteger zipRow = [picker selectedRowInComponent:kZipComponent];

    NSString *state = [self.states objectAtIndex:stateRow];
    NSString *zip = [self.zips objectAtIndex:zipRow];

    NSString *title = [[NSString alloc] initWithFormat:@"You selected zip code %@.", zip];
    NSString *message = [[NSString alloc] initWithFormat:@"%@ is in %@", zip, state];

    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:title message:message delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
    [alert show];
    [alert release];
    [title release];
    [message release];
}

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

- (void)viewDidLoad {

    NSBundle *bundle = [NSBundle mainBundle];
    NSString *plistPath = [bundle pathForResource:@"statedictionary" ofType:@"plist"];
    NSDictionary *dictionary = [[NSDictionary alloc] initWithContentsOfFile:plistPath];
    self.stateZips = dictionary;
    [dictionary release];

    NSArray *components = [self.stateZips allKeys];
    NSArray *sorted = [components sortedArrayUsingSelector:@selector(compare:)];
    self.states = sorted;

    NSString *selectedState = [self.states objectAtIndex:0];
    NSArray *array = [stateZips objectForKey:selectedState];
    self.zips = array;
}

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

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning]; // Releases the view if it doesn't have a superview
    // Release anything that's not essential, such as cached data
}

- (void)dealloc {   
    [picker release];
    [stateZips release];
    [states release];
    [zips release];
    [super dealloc];
}

#pragma mark -
#pragma mark Picker Data Source Methods
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
{
    return 2;
}

- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
{
    if (component == kStateComponent)
        return [self.states count];
    return [self.zips count];
}

#pragma mark Picker Delegate Methods
- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
{
    if (component == kStateComponent)
        return [self.states objectAtIndex:row];
    return [self.zips objectAtIndex:row];
}

- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
{
    if (component == kStateComponent)
    {
        NSString *selectedState = [self.states objectAtIndex:row];
        NSArray *array = [stateZips objectForKey:selectedState];
        self.zips = array;
        [picker selectRow:0 inComponent:kZipComponent animated:YES];
        [picker reloadComponent:kZipComponent];
    }
}

- (CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component
{
    if (component == kZipComponent)
        return 90;
    return 205;
}
@end

在这个例子中使用了 NSDictionary，但你也可以只使用数组。

不客气，

阿里尔多