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标题: ios - 在数据库Objective C中本地保存JSON响应 [打印本页]

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作者: 菜鸟教程小白    时间: 2022-12-12 13:26
标题: ios - 在数据库Objective C中本地保存JSON响应

我有一个用于 GET API 请求的 questioAnswer responseObject:

{"7d2c591c-9056-405c-9509-03266842b7e5"=();"f884a7d1-f9d9-4563-bb6e-94538664f3bd"=test;}

如何根据特定的调查 uuid 将其本地保存在数据库中？

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Best Answer-推荐答案

您可以将其保存在 session 中。

设置:

NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];

[userDefaults setObject:value 
                 forKey:key];
[userDefaults synchronize];

获取:

[[NSUserDefaults standardUserDefaults] objectForKey:key];

编辑

只是为了说明将 Core Data 添加到以前没有的项目中实际需要执行的所有步骤:

第 1 步:添加框架

点击您的应用程序目标(在左侧 Pane 中，其顶部图标带有您的应用程序名称)，然后转到“构建阶段”选项卡，然后在“将二进制文件与库链接”上，单击小“+”在底部然后找到'CoreData.framework'并将其添加到您的项目中

然后使用以下方法在您需要的所有对象上导入 coredata(非性感方式):

swift

import CoreData

Objective-C

#import <CoreData/CoreData.h>

或在 .pch 文件中的常见导入下方添加导入(更性感)，如下所示:

#ifdef __OBJC__
    #import <UIKit/UIKit.h>
    #import <Foundation/Foundation.h>
    #import <CoreData/CoreData.h>
#endif

第 2 步:添加数据模型

要添加 .xcdatamodel 文件，请在右侧 Pane 中右键单击/控制单击您的文件(例如在资源文件夹中以确保安全)并选择添加新文件，在选择文件类型时单击核心数据选项卡然后单击“数据模型”，为其命名并单击下一步和完成，它将将其添加到您的项目中。当您单击此模型对象时，您将看到将实体添加到您的项目的界面以及您想要的任何关系。

第 3 步:更新 App Delegate

在 AppDelegate.swift 上的 Swift 中

//replace the previous version of applicationWillTerminate with this
func applicationWillTerminate(application: UIApplication) {
    // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
    // Saves changes in the application's managed object context before the application terminates.
    self.saveContext()
}

func saveContext () {
    var error: NSError? = nil
    let managedObjectContext = self.managedObjectContext
    if managedObjectContext != nil {
        if managedObjectContext.hasChanges && !managedObjectContext.save(&error) {
            // Replace this implementation with code to handle the error appropriately.
            // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
            //println("Unresolved error \(error), \(error.userInfo)")
            abort()
        }
    }
}

// #pragma mark - Core Data stack

// Returns the managed object context for the application.
// If the context doesn't already exist, it is created and bound to the persistent store coordinator for the application.
var managedObjectContext: NSManagedObjectContext {
    if !_managedObjectContext {
        let coordinator = self.persistentStoreCoordinator
        if coordinator != nil {
            _managedObjectContext = NSManagedObjectContext()
            _managedObjectContext!.persistentStoreCoordinator = coordinator
        }
    }
    return _managedObjectContext!
}
var _managedObjectContext: NSManagedObjectContext? = nil

// Returns the managed object model for the application.
// If the model doesn't already exist, it is created from the application's model.
var managedObjectModel: NSManagedObjectModel {
    if !_managedObjectModel {
        let modelURL = NSBundle.mainBundle().URLForResource("iOSSwiftOpenGLCamera", withExtension: "momd")
        _managedObjectModel = NSManagedObjectModel(contentsOfURL: modelURL)
    }
    return _managedObjectModel!
}
var _managedObjectModel: NSManagedObjectModel? = nil

// Returns the persistent store coordinator for the application.
// If the coordinator doesn't already exist, it is created and the application's store added to it.
var persistentStoreCoordinator: NSPersistentStoreCoordinator {
    if !_persistentStoreCoordinator {
        let storeURL = self.applicationDocumentsDirectory.URLByAppendingPathComponent("iOSSwiftOpenGLCamera.sqlite")
        var error: NSError? = nil
        _persistentStoreCoordinator = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)
        if _persistentStoreCoordinator!.addPersistentStoreWithType(NSSQLiteStoreType, configuration: nil, URL: storeURL, options: nil, error: &error) == nil {
            /*
            Replace this implementation with code to handle the error appropriately.
            abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
            Typical reasons for an error here include:
            * The persistent store is not accessible;
            * The schema for the persistent store is incompatible with current managed object model.
            Check the error message to determine what the actual problem was.
            If the persistent store is not accessible, there is typically something wrong with the file path. Often, a file URL is pointing into the application's resources directory instead of a writeable directory.
            If you encounter schema incompatibility errors during development, you can reduce their frequency by:
            * Simply deleting the existing store:
            NSFileManager.defaultManager().removeItemAtURL(storeURL, error: nil)
            * Performing automatic lightweight migration by passing the following dictionary as the options parameter:
            [NSMigratePersistentStoresAutomaticallyOption: true, NSInferMappingModelAutomaticallyOption: true}
            Lightweight migration will only work for a limited set of schema changes; consult "Core Data Model Versioning and Data Migration Programming Guide" for details.
            */
            //println("Unresolved error \(error), \(error.userInfo)")
            abort()
        }
    }
    return _persistentStoreCoordinator!
}
var _persistentStoreCoordinator: NSPersistentStoreCoordinator? = nil

// #pragma mark - Application's Documents directory

// Returns the URL to the application's Documents directory.
var applicationDocumentsDirectory: NSURL {
    let urls = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)
    return urls[urls.endIndex-1] as NSURL
}

在 Objective C 中，确保将这些对象添加到 AppDelegate.h

 @property (nonatomic, retain, readonly) NSManagedObjectModel *managedObjectModel;
 @property (nonatomic, retain, readonly) NSManagedObjectContext *managedObjectContext;
 @property (nonatomic, retain, readonly) NSPersistentStoreCoordinator *persistentStoreCoordinator;

 - (NSURL *)applicationDocumentsDirectory; // nice to have to reference files for core data

像这样在 AppDelegate.m 中合成之前的对象:

@synthesize managedObjectContext = _managedObjectContext;
@synthesize managedObjectModel = _managedObjectModel;
@synthesize persistentStoreCoordinator = _persistentStoreCoordinator;

然后将这些方法添加到 AppDelegate.m(确保将您添加的模型的名称放在显示的位置):

- (void)saveContext{
    NSError *error = nil;
    NSManagedObjectContext *managedObjectContext = self.managedObjectContext;
    if (managedObjectContext != nil) {
        if ([managedObjectContext hasChanges] && ![managedObjectContext save:&error]) {
            NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
            abort();
        }
    }
}

- (NSManagedObjectContext *)managedObjectContext{
    if (_managedObjectContext != nil) {
        return _managedObjectContext;
    }

    NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];
    if (coordinator != nil) {
        _managedObjectContext = [[NSManagedObjectContext alloc] init];
        [_managedObjectContext setPersistentStoreCoordinator:coordinator];
    }
    return _managedObjectContext;
}

- (NSManagedObjectModel *)managedObjectModel{
    if (_managedObjectModel != nil) {
        return _managedObjectModel;
    }
    NSURL *modelURL = [[NSBundle mainBundle] URLForResource"NAMEOFYOURMODELHERE" withExtension"momd"];
    _managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
    return _managedObjectModel;
}

- (NSPersistentStoreCoordinator *)persistentStoreCoordinator
{
    if (_persistentStoreCoordinator != nil) {
        return _persistentStoreCoordinator;
    }

    NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent"NAMEOFYOURMODELHERE.sqlite"];

    NSError *error = nil;
    _persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
    if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error]) {

        NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
        abort();
    }

    return _persistentStoreCoordinator;
}

 #pragma mark - Application's Documents directory

// Returns the URL to the application's Documents directory.
- (NSURL *)applicationDocumentsDirectory{
    return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
}

第 4 步:将数据对象获取到需要数据的 ViewControllers

选项 1. 使用来自 VC 的 App Delegate 的 ManagedObjectContext(首选且更简单)

正如@brass-kazoo 所建议的那样——通过以下方式检索对 AppDelegate 及其 managedObjectContext 的引用:

swift

let appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
 appDelegate.managedObjectContext

Objective-C

 [[[UIApplication sharedApplication] delegate] managedObjectContext];

选项 2. 在您的 VC 中创建 ManagedObjectContext 并使其与 AppDelegate 中的 AppDelegate 匹配(原始)

只显示 Objective C 的旧版本，因为更容易使用首选方法

在 ViewController.h 中

@property (nonatomic, retain) NSManagedObjectContext *managedObjectContext;

在 ViewController.m 中

@synthesize managedObjectContext = _managedObjectContext;

在 AppDelegate 或创建 ViewController 的类中，将 managedObjectContext 设置为与 AppDelegate 相同

ViewController.managedObjectContext = self.managedObjectContext;

如果您希望使用 Core Data 的 View Controller 成为 FetchedResultsController，那么您需要确保这些内容在您的 ViewController.h 中

@interface ViewController : UIViewController <NSFetchedResultsControllerDelegate> {
  NSFetchedResultsController *fetchedResultsController;
  NSManagedObjectContext *managedObjectContext;
}

 @property (nonatomic, retain) NSFetchedResultsController *fetchedResultsController;

这是在 ViewController.m 中

@synthesize fetchedResultsController, managedObjectContext;

在所有这些之后，您现在可以使用这个 managedObjectContext 来运行 CoreData 所需的所有常用 fetchRequest!享受

关于ios - 在数据库Objective C中本地保存JSON响应，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/44047580/

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