Question

我想在coredata ta

中插入50个值

 Question.h

#import <Foundation/Foundation.h>
#import <CoreData/CoreData.h>


@interface Question : NSManagedObject

@property (nonatomic, retain) NSString * question;
@property (nonatomic, retain) NSString * answer;
@property (nonatomic, retain) NSString * mcqsa;
@property (nonatomic, retain) NSString * mcqsb;
@property (nonatomic, retain) NSString * mcqsc;
@property (nonatomic, retain) NSString * mcqsd;



Question.m
#import "Question.h"


@implementation Question

@dynamic question;
@dynamic answer;  
@dynamic mcqsa;
@dynamic mcqsb;
@dynamic mcqsc;
@dynamic mcqsd;

@end

插入代码

 - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
 {

    NSManagedObjectContext *context = [self managedObjectContext];


    Question *question = [NSEntityDescription
                                  insertNewObjectForEntityForName:@"Question"
                                  inManagedObjectContext:context];
question.question = @"What is capital of Australia?";
question.answer = @"Testville";
question.mcqsa = @"Sydney";
question.mcqsb = @"Canbera";
question.mcqsc =  @"Berlin";
question.mcqsd = @"Bern";

NSError *error;
if (![context save:&error]) {
    NSLog(@"Whoops, couldn't save: %@", [error localizedDescription]);
}
.......

如何使用mcqs插入多个数据，50个问题（50个问题对象）？是否有任何手动方式使用别的东西？

Answer 1

MagicalRecord CoreData的包装器提供了一些很好的导入功能。您需要在bundle中包含作为plist / json导入的数据。

在初始运行时，您将数据导入coreData。

您可以在以下链接Importing data made easy

中找到相同的精彩教程

您需要创建NSManagedObject的子类

您可以致电importFromObject:或importFromObject:。如果您可以完全控制数据的结构，那么这将是开箱即用的，而无需编写单个代码来映射存储到核心数据实体的数据。

Answer 2

您需要种子存储，预填充核心数据数据库，然后从设备或模拟器文档目录中获取它，然后将其添加到您的包中。首次运行时，您可以将数据库从bundle复制到Document目录，然后使用该数据库

Answer 3

您可以使用for循环插入数据。

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
 {
for(i=0; i<50; i++) {
    NSManagedObjectContext *context = [self managedObjectContext];


    Question *question = [NSEntityDescription
                                  insertNewObjectForEntityForName:@"Question"
                                  inManagedObjectContext:context];
question.question = @"What is capital of Australia?";
question.answer = @"Testville";
question.mcqsa = @"Sydney";
question.mcqsb = @"Canbera";
question.mcqsc =  @"Berlin";
question.mcqsd = @"Bern";

NSError *error;
if (![context save:&error]) {
    NSLog(@"Whoops, couldn't save: %@", [error localizedDescription]);
}
.......
}

Answer 4

enter image description here 以下是代码：

  NSString* plistPath = [[NSBundle mainBundle] pathForResource:@"QuesList" ofType:@"plist"];


   NSArray *quesList = [[NSArray alloc]initWithContentsOfFile:plistPath];


    for(NSDictionary *object in quesList){


NSString *str1 = [object objectForKey:@"question"];
NSString *str2 = [object objectForKey:@"answer"];
NSString *str3 = [object objectForKey:@"mcqsa"];
NSString *str4 = [object objectForKey:@"mcqsb"];
NSString *str5 = [object objectForKey:@"mcqsc"];



 Question *question = [NSEntityDescription
                          insertNewObjectForEntityForName:@"Question"
                          inManagedObjectContext:context];
question.question = str1;
question.answer =str2;
question.mcqsa =str3;
question.mcqsb =str4;
question.mcqsc =  str5;

  }

并且

还要确保只运行一次此代码，否则它会创建重复的对象

在核心数据表中插入50个对象

4 个答案: