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我不熟悉 IOS 编程和构建我的核心数据概念。我遵循苹果文档中的指南。我有一个 TableView Controller 和一个可变数组 StocksArray 作为其属性之一。我有另一个 View DetailedController，它用于为核心数据模型的实体属性获取用户输入。我将 NSManagedObject 传递到 DetailedController 对象并使用委托(delegate)来更新可变数组 StocksArray。编译时出现错误——由于未捕获的异常“NSInvalidArgumentException”而终止应用程序，原因:“* -[NSMutableArray insertObject:atIndex:]: attempt to insert nil object at 0”。如果有人能帮助我，我将不胜感激。
#import"StockEntity.h"
@protocol DetailedControllerdelegate <NSObject>
-(void)addstockinarray:(StockEntity*)anObject;
@end
@interface DetailedController : UIViewController {
IBOutlet UITextField* stocksymboltextfield;
IBOutlet UITextField* stocknametextfield;
//NSManagedObjectContext* context2;
StockEntity* asinglestock;
}
@property (nonatomic, retain) IBOutlet UITextField* stocksymboltextfield;
@property (nonatomic, retain) IBOutlet UITextField* stocknametextfield;
//@property(nonatomic, retain) NSManagedObjectContext* context2;
@property(nonatomic, retain) StockEntity* asinglestock;
@property (nonatomic, assign) id <DetailedControllerdelegate> delegate;
@implementation DetailedController
@synthesize stocksymboltextfield, stocknametextfield,asinglestock, delegate;//context2;
-(void)onDone:(id)sender{
[asinglestock setStockName:self.stocknametextfield.text];
[asinglestock setStockSymbol:self.stocksymboltextfield.text];
NSLog(@"lets s see: %@", [asinglestock StockName]);
NSError *error = nil;
if (![[asinglestock managedObjectContext] save:&error] ) {
//handle the error
}
if ([delegate respondsToSelector:@selector(addstockinarray:)]) {
NSLog(@"before delegate");
[delegate addstockinarray:asinglestock];
NSLog(@"am in delegate");
}
[self.navigationController popViewControllerAnimated:YES];
}
这是 TableView 的实现
@implementation maintable
@synthesize stocksArray, managedObjectContext, addButton;
- (id)initWithStyle:(UITableViewStyle)style {
self = [super initWithStyle:style];
if (self) {
// Custom initialization.
self.stocksArray =[[NSMutableArray alloc]init];
}
return self;
}
- (void)viewDidLoad {
[super viewDidLoad];
//self.stocksArray =[[NSMutableArray alloc]init];
self.title = @"Stocks";
// Uncomment the following line to display an Edit button in the navigation bar for this view controller.
self.navigationItem.leftBarButtonItem = self.editButtonItem;
addButton = [[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemAdd
target:self
action:@selector(addStock)];
//addButton.enabled = NO;
self.navigationItem.rightBarButtonItem = addButton;
}
-(void) addStock{
DetailedController *detail = [[DetailedController alloc]initWithNibName:NSStringFromClass([DetailedController class]) bundle:[NSBundle mainBundle]];
//detail.context2 = managedObjectContext;
StockEntity *stock = (StockEntity*)[NSEntityDescription insertNewObjectForEntityForName:@"StockEntity"
inManagedObjectContext:managedObjectContext];
detail.asinglestock = stock;
detail.delegate = self;
//[stocksArray insertObject:stock atIndex:0];
[self.navigationController pushViewController:detail animated:YES];
[detail release];
}
-(void)addstockinarray:(StockEntity*)anObject{
if (anObject = NULL) {
NSLog(@"YESSS");
}
[self.stocksArray addObject:anObject];
NSLog(@"LETTTTTT: %i", [self.stocksArray count] );
}
- (void)viewWillAppear:(BOOL)animated {
[self.tableView reloadData];
[super viewWillAppear:animated];
}