ios：UIPickerView lldb錯誤，當我嘗試滾動

Question

我有一個視圖，需要等待，直到從Web服務檢索數據，然後更新UI選取器視圖。當我在等待響應，如果用戶滾動選擇器視圖的應用程序崩潰，我得到lldb錯誤。任何理由？

這裏是我的代碼：

@interface LocavoreRetroSecondViewController() 

@end 

@implementation LocavoreRetroSecondViewController 

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil 
{ 
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]; 
    if (self) { 
     self.title = NSLocalizedString(@"I Ate Local", @"I Ate Local"); 
     self.tabBarItem.image = [UIImage imageNamed:@"newfood"]; 
     _dataController = [[InSeasonProductDataController alloc] init]; 
    } 
    return self; 
} 

- (void)viewDidLoad 
{ 
    [super viewDidLoad]; 

} 

- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView { 
    return 1; 
} 

- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component { 
    return [_dataController countOfList]; 
} 
- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component { 
    Product *product = [_dataController objectInListAtIndex:row]; 
    return product.name; 
} 

- (void)pickerView:(UIPickerView *)thePickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component { 

    //do something 
} 



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

- (void)dealloc{ 
    [_dataController release]; 
    [super dealloc]; 
} 

我得到這個錯誤：

*斷言失敗 - [UITableViewRowData rectForRow：切入口：]，/SourceCache/UIKit_Sim/UIKit-2380.17/UITableViewRowData的.m：1630 （LLDB）

Answer 1

更改碼本：

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

if ([_dataController countOfList]>0) { 
    return [_dataController countOfList]; 
}else{ 
    return 1; 
} 

} 

- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component { 
if ([_dataController countOfList]>0) { 
Product *product = [_dataController objectInListAtIndex:row]; 
return product.name; 
}else{ 
    return @""; 
} 
}