ios Core Data - 我的保存按钮不起作用

Posted 2023-05-07

【中文标题】ios Core Data - 我的保存按钮不起作用

【英文标题】：ios Coredata - my savebutton is not working

【发布时间】：2012-11-18 04:23:12

【问题描述】：

我正在尝试为我的 CoreData 项目制作一个保存按钮，通常我没有任何问题。但这次我没有看到它保存到 SQL 文件（在 FireFox 中使用 SQLite），也无法将数据拉回 UITableView。

没有错误或警告。有人可以帮我解决周日下午（新西兰时间）阴天的问题吗？？

- (IBAction)saveDataAction:(id)sender

//Instantiating the Entity with a pointer and giving it a mission.
NSString *details = @"Details";
NSManagedObject *newObject = [NSEntityDescription insertNewObjectForEntityForName:details inManagedObjectContext:[self managedObjectContext]];

int yearOfBirth = [_yearTxtField.text intValue]; //Converting the value from a String into an int
NSNumber *year = [NSNumber numberWithInt:yearOfBirth]; //Converting the int into a NSNumber

//Setting each textField value to an attribute in the Entity.
[newObject setValue:_nameTxtField.text forKey:@"name"];
[newObject setValue:_streetTxtField.text forKey:@"streetName"];
[newObject setValue:_cityTxtField.text forKey:@"cityName"];
[newObject setValue:year forKey:@"yearOfBirth"];

//This log just shows what has been added to the database.
//NSLog(@"Details Save:\n\n Name: %@\n StreetName: %@\n CityName: %@\n Year of birth: %@", details.name, details.streetName, details.cityName, details.yearOfBirth);

【问题讨论】：

在上下文中添加对象后需要保存上下文。试试我的代码

【参考方案1】：

- (IBAction)saveDataAction:(id)sender

     //Instantiating the Entity with a pointer and giving it a mission.
    NSString *details = @"Details";
    NSManagedObjectContext *context = [self managedObjectContext];
    NSManagedObject *newObject = [NSEntityDescription insertNewObjectForEntityForName:details inManagedObjectContext:context];

    int yearOfBirth = [_yearTxtField.text intValue]; //Converting the value from a String into an int
    NSNumber *year = [NSNumber numberWithInt:yearOfBirth]; //Converting the int into a NSNumber

    //Setting each textField value to an attribute in the Entity.
    [newObject setValue:_nameTxtField.text forKey:@"name"];
    [newObject setValue:_streetTxtField.text forKey:@"streetName"];
    [newObject setValue:_cityTxtField.text forKey:@"cityName"];
    [newObject setValue:year forKey:@"yearOfBirth"];

    NSError *error;
    if (![context save:&error]) 
        NSLog(@"Whoops couldn't save new object");
    
    //This log just shows what has been added to the database.
    //NSLog(@"Details Save:\n\n Name: %@\n StreetName: %@\n CityName: %@\n Year of birth: %@", details.name, details.streetName, details.cityName, details.yearOfBirth);

【讨论】：

一旦你完成删除、更新或插入，你总是需要保存上下文。不要忘记 :-) @JeffKranenburg。