Ios +；entityForName:nil不是搜索实体名称的合法NSManagedObjectContext参数'；账户''；

我尝试了很多选择，但找不到解决这个问题的方法。我创建了一个核心数据文件，命名为实体帐户，创建了一个名为username的字符串属性。然后将实体的类编辑为NSManagedObject，不确定这是否正确。现在，我的LoginViewController中有以下代码：

- (void)viewDidLoad
{
    [super viewDidLoad];

    ITAppDelegate *appDelegate = (ITAppDelegate *)[[UIApplication sharedApplication] delegate];
    NSManagedObjectContext *context = appDelegate.managedObjectContext;

    Account *newAccount = [NSEntityDescription insertNewObjectForEntityForName:@"Account" inManagedObjectContext:context];
    [newAccount setValue:@"Jorge" forKey:@"username"];
    [newAccount setPassword:@"password"];

    NSLog(@"username:%@   password: %@", [newAccount username], [newAccount password]);

}

我遵循了以下步骤，我的代码文件如下所示：

ITAppDelegate.h

#import <UIKit/UIKit.h>

@interface ITAppDelegate : UIResponder <UIApplicationDelegate>

@property (strong, nonatomic) UIWindow *window;

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

@end

AccountBase.h

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

@interface AccountBase : NSManagedObject

@property (nonatomic, retain) NSString *username;


@end

账户.h

#import "AccountBase.h"
#import <CoreData/CoreData.h>

@interface Account : AccountBase

@property (nonatomic, assign) NSString *password;

@end

KeychainHelper.h

#import <Foundation/Foundation.h>

@interface KeychainHelper : NSObject

+ (NSString*)getPasswordForKey:(NSString*)aKey;
+ (void)setPassword:(NSString*)aPassword forKey:(NSString*)aKey;
+ (void)removePasswordForKey:(NSString*)aKey;

@end

#导入
@接口KeychainHelper:NSObject
+（NSString*）getPasswordForKey:（NSString*）aKey；
+（void）setPassword:（NSString*）aPassword forKey:（NSString*）aKey；
+（void）移除passwordforkey:（NSString*）aKey；
@结束

KeychainHelper.m

#import "KeychainHelper.h"
#import <Security/Security.h>

@interface KeychainHelper ()
+ (NSMutableDictionary*)dictionaryForKey:(NSString*)aKey;
@end

@implementation KeychainHelper


static const NSString *ironTrainers = @"com.domain.myapplication";

+ (NSMutableDictionary*)dictionaryForKey:(NSString*)aKey
{
    NSData *encodedKey = [aKey dataUsingEncoding:NSUTF8StringEncoding];

    NSMutableDictionary *searchDictionary = [NSMutableDictionary dictionary];

    [searchDictionary setObject:(__bridge id)kSecClassGenericPassword forKey:(__bridge id)kSecClass];
    [searchDictionary setObject:encodedKey forKey:(__bridge id)kSecAttrGeneric];
    [searchDictionary setObject:encodedKey forKey:(__bridge id)kSecAttrAccount];
    [searchDictionary setObject:ironTrainers forKey:(__bridge id)kSecAttrService];

    return searchDictionary;
}  

+ (NSString*)getPasswordForKey:(NSString*)aKey
{
    NSString *password = nil;

    NSMutableDictionary *searchDictionary = [self dictionaryForKey:aKey];
    [searchDictionary setObject:(__bridge id)kSecMatchLimitOne forKey:(__bridge id)kSecMatchLimit];
    [searchDictionary setObject:(id)kCFBooleanTrue forKey:(__bridge id)kSecReturnData];

    CFTypeRef result = NULL;
    BOOL statusCode = SecItemCopyMatching((__bridge CFDictionaryRef)searchDictionary, &result);
    if (statusCode == errSecSuccess) {
        NSData *resultData = CFBridgingRelease(result);
        password = [[NSString alloc] initWithData:resultData encoding:NSUTF8StringEncoding];
    }
    return (__bridge NSString *)(result);
}

+ (void)removePasswordForKey:(NSString*)aKey
{
    NSMutableDictionary *keyDictionary = [self dictionaryForKey:aKey];
    SecItemDelete((__bridge CFDictionaryRef)keyDictionary);
 }

+ (void)setPassword:(NSString*)aPassword forKey:(NSString*)aKey
{
    [KeychainHelper removePasswordForKey:aKey];

    NSData *encodedPassword = [aPassword dataUsingEncoding:NSUTF8StringEncoding];

    NSMutableDictionary *keyDictionary = [self dictionaryForKey:aKey];
    [keyDictionary setObject:encodedPassword forKey:(__bridge id)kSecValueData];
    SecItemAdd((__bridge CFDictionaryRef)keyDictionary, nil);
}

@end

#导入“KeychainHelper.h”
#进口
@接口KeychainHelper（）
+（NSMutableDictionary*）字典工作：（NSString*）aKey；
@结束
@实现KeychainHelper
静态常量NSString*ironTrainers=@“com.domain.myapplication”；
+（NSMutableDictionary*）字典工作：（NSString*）aKey
{
NSData*encodedKey=[aKey DATAUSINGENCODE:NSUTF8StringEncoding]；
NSMutableDictionary*searchDictionary=[NSMutableDictionary]；
[searchDictionary setObject:（uu桥id）kSecClassGenericPassword forKey:（uu桥id）kSecClass]；
[searchDictionary setObject:encodedKey-forKey:（u桥id）kSecAttrGeneric]；
[searchDictionary setObject:encodedKey-forKey:（u桥id）kSecAttrAccount]；
[searchDictionary setObject:ironTrainers-forKey:（uu桥id）kSecAttrService]；
返回搜索词典；
}  
+（NSString*）getPasswordForKey:（NSString*）aKey
{
NSString*密码=nil；
NSMutableDictionary*searchDictionary=[self dictionaryworky:aKey]；
[searchDictionary setObject:（u桥id）kSecMatchLimitOne-forKey:（u桥id）kSecMatchLimit]；
[searchDictionary setObject:（id）kCFBooleanTrue forKey:（_桥id）kSecReturnData]；
CFTypeRef结果=NULL；
BOOL statusCode=SecItemCopyMatching（（uu桥CFDictionaryRef）搜索字典，&结果）；
if（statusCode==errSecSuccess）{
NSData*resultData=CfBrigingRelease（结果）；
密码=[[NSString alloc]initWithData:resultData编码：NSUTF8StringEncoding]；
}
返回（_桥NSString*）（结果）；
}
+（void）removePasswordForKey:（NSString*）aKey
{
NSMutableDictionary*keyDictionary=[self dictionaryWorkey:aKey]；
SecItemDelete（（uu桥CFDictionaryRef）键字典）；
}
+（void）setPassword:（NSString*）aPassword forKey:（NSString*）aKey
{
[KeychainHelper removePasswordForKey:aKey]；
NSData*encodedPassword=[aPassword dataUsingEncoding:NSUTF8StringEncoding]；
NSMutableDictionary*keyDictionary=[self dictionaryWorkey:aKey]；
[keyDictionary setObject:encodedPassword forKey:（_桥id）kSecValueData]；
SecItemAdd（（uu桥CFDictionaryRef）键字典，无）；
}
@结束

---

谢谢你的帮助。谢谢。

这可能是因为实体名与其类名不匹配。确保您的帐户实体在.xcdatamodeld文件中具有适当的类名

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

    NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];
    if (coordinator != nil) {

        managedObjectContext = [[NSManagedObjectContext alloc] init];
        [managedObjectContext setPersistentStoreCoordinator:coordinator];
    }
    return managedObjectContext;
}

• 您尚未提供

  persistentstorecordinator

• 因此，

  协调器

  将始终为

  nil

• 因此，您将始终从此方法返回

  nil

• 这意味着您将始终得到上面的错误

要解释错误，请执行以下操作：

+entityForName:nil不是搜索实体名称“Account”的合法NSManagedObjectContext参数

阅读它并不能立即看出这一点，但这意味着对于托管对象上下文来说，

nil

不是一个合法的东西。乍一看，您似乎在做

entityForName:nil

，但事实并非如此

---

要解决此问题，您需要提供有效的持久存储协调器。我有一篇小文章，解释了设置核心数据堆栈所需的代码有多少，这可能会对您有所帮助

在我的例子中，我使用具有不同并发类型的多个上下文（父/子上下文）来提高性能。我有三个背景：

storeContext

这是唯一设置了

persistentStoreCoordinator

的上下文

viewContext

其父项是

storeContext

backgroundContext

其父项应该是

viewContext

，但我忘记设置

backgroundContext.parent=viewContext

在

backgroundContext

上保存实体时会产生相同的错误

+entityForName:nil不是搜索实体名称的合法NSManagedObjectContext参数

…因为

backgroundContext

不是父/子上下文链的一部分

---

将

backgroundContext

的

parent

设置为

viewContext

将链建立回持久存储协调员并解决了错误。

我遇到了此

entityForName:nil

错误，但它最终有点像是转移视线，只有在我的CI上运行单元测试时才会显现出来。在测试过程中，应用程序遇到了一些奇怪的线程问题，这些问题是由。在从HTML创建

NSAttributedString

的同时，向主队列进行异步调度以与核心数据交互

---

只是在这里发布我的经验，以防它最终帮助其他人。：）

从核心数据中提取数据时，我遇到了相同的错误。原因是未正确设置上下文对象的值，并且在获取结果后将其设置为该值。因此，在点击fetch请求之前正确设置上下文可以完成工作。

错误消息表明managedObjectContext参数为nil，这与模型无关谢谢，它对用户名有效。我改变

#import <Foundation/Foundation.h>

@interface KeychainHelper : NSObject

+ (NSString*)getPasswordForKey:(NSString*)aKey;
+ (void)setPassword:(NSString*)aPassword forKey:(NSString*)aKey;
+ (void)removePasswordForKey:(NSString*)aKey;

@end

#import "KeychainHelper.h"
#import <Security/Security.h>

@interface KeychainHelper ()
+ (NSMutableDictionary*)dictionaryForKey:(NSString*)aKey;
@end

@implementation KeychainHelper


static const NSString *ironTrainers = @"com.domain.myapplication";

+ (NSMutableDictionary*)dictionaryForKey:(NSString*)aKey
{
    NSData *encodedKey = [aKey dataUsingEncoding:NSUTF8StringEncoding];

    NSMutableDictionary *searchDictionary = [NSMutableDictionary dictionary];

    [searchDictionary setObject:(__bridge id)kSecClassGenericPassword forKey:(__bridge id)kSecClass];
    [searchDictionary setObject:encodedKey forKey:(__bridge id)kSecAttrGeneric];
    [searchDictionary setObject:encodedKey forKey:(__bridge id)kSecAttrAccount];
    [searchDictionary setObject:ironTrainers forKey:(__bridge id)kSecAttrService];

    return searchDictionary;
}  

+ (NSString*)getPasswordForKey:(NSString*)aKey
{
    NSString *password = nil;

    NSMutableDictionary *searchDictionary = [self dictionaryForKey:aKey];
    [searchDictionary setObject:(__bridge id)kSecMatchLimitOne forKey:(__bridge id)kSecMatchLimit];
    [searchDictionary setObject:(id)kCFBooleanTrue forKey:(__bridge id)kSecReturnData];

    CFTypeRef result = NULL;
    BOOL statusCode = SecItemCopyMatching((__bridge CFDictionaryRef)searchDictionary, &result);
    if (statusCode == errSecSuccess) {
        NSData *resultData = CFBridgingRelease(result);
        password = [[NSString alloc] initWithData:resultData encoding:NSUTF8StringEncoding];
    }
    return (__bridge NSString *)(result);
}

+ (void)removePasswordForKey:(NSString*)aKey
{
    NSMutableDictionary *keyDictionary = [self dictionaryForKey:aKey];
    SecItemDelete((__bridge CFDictionaryRef)keyDictionary);
 }

+ (void)setPassword:(NSString*)aPassword forKey:(NSString*)aKey
{
    [KeychainHelper removePasswordForKey:aKey];

    NSData *encodedPassword = [aPassword dataUsingEncoding:NSUTF8StringEncoding];

    NSMutableDictionary *keyDictionary = [self dictionaryForKey:aKey];
    [keyDictionary setObject:encodedPassword forKey:(__bridge id)kSecValueData];
    SecItemAdd((__bridge CFDictionaryRef)keyDictionary, nil);
}

@end

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

    NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];
    if (coordinator != nil) {

        managedObjectContext = [[NSManagedObjectContext alloc] init];
        [managedObjectContext setPersistentStoreCoordinator:coordinator];
    }
    return managedObjectContext;
}