Error: CoreData 之 unrecognized selector sent to instance - iOS

在对 CoreData 写增删改查方法之后编译工程 run 的时候抛出了 unrecognized selector sent to instance 的异常；

全局断点停留的位置并非异常的出处，起初很懵，不过既然是因为操作 CoreData 后才出现的异常，无疑肯定问题是出在了这里，经过前后的排查 code 逻辑，最终发现了问题的所在，好大意所导致！

具体详见 code：

一、异常 code

#pragma mark - ************************************ Insert
+ (void)insertObjForEntityWithDataSource:(NSDictionary *)dataSource ResultState:(void (^)(BOOL, NSError * _Nonnull))result {
    CoreDataManager *dataManager = [CoreDataManager sharedCoreDataManager];
    
    // Query
    NSString *key = [NSString stringWithFormat:@"%@", [dataSource objectForKey:@"key"]];
    NSFetchRequest *request = [[NSFetchRequest alloc] init];
    NSEntityDescription *entity = [NSEntityDescription entityForName:EntityName
                                              inManagedObjectContext:dataManager.managedObjectContext];
    [request setEntity:entity];
    
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"key=%@", key];
    [request setPredicate:predicate];
    
    NSError *error;
    NSArray *resultData = [dataManager.managedObjectContext executeFetchRequest:request
                                                                          error:&error];
    
    if (kArrayIsEmpty(resultData)) {// Insert new obj to entity
        NSLog(@"CoreData --- Insert new obj entity --- %@", EntityName);
        
        User *userEntity = [NSEntityDescription insertNewObjectForEntityForName:EntityName
                                                        inManagedObjectContext:dataManager.managedObjectContext];
        userEntity.imei = [NSString stringWithFormat:@"%@", [dataSource objectForKey:@"imei"]];
        userEntity.userType = [NSString stringWithFormat:@"%@", [dataSource objectForKey:@"userType"]];
        userEntity.project = [NSString stringWithFormat:@"%@", [dataSource objectForKey:@"project"]];
        
    } else {// Update current entity operation
        NSLog(@"CoreData --- Update current entity operation --- %@", EntityName);
        
        for (User *userEntity in dataSource) {
            if ([userEntity.key isEqualToString:key]) {
                userEntity.imei = [NSString stringWithFormat:@"%@", [dataSource objectForKey:@"imei"]];
                userEntity.userType = [NSString stringWithFormat:@"%@", [dataSource objectForKey:@"userType"]];
                userEntity.project = [NSString stringWithFormat:@"%@", [dataSource objectForKey:@"project"]];
            }
        }
    }
    
    if (error) {
        NSLog(@"****** CoreData Error - [%@] insert obj for entity ******\n%@", EntityName, error);
    }
    
    // Save processing result
    BOOL saveState = [dataManager.managedObjectContext save:&error];
    // Callback result state
    if (result) {
        result(saveState, error);
    }
}

二、排除异常之后的 code

#pragma mark - ************************************ Insert
+ (void)insertObjForEntityWithDataSource:(NSDictionary *)dataSource ResultState:(void (^)(BOOL, NSError * _Nonnull))result {
    CoreDataManager *dataManager = [CoreDataManager sharedCoreDataManager];
    
    // Query
    NSString *key = [NSString stringWithFormat:@"%@", [dataSource objectForKey:@"key"]];
    NSFetchRequest *request = [[NSFetchRequest alloc] init];
    NSEntityDescription *entity = [NSEntityDescription entityForName:EntityName
                                              inManagedObjectContext:dataManager.managedObjectContext];
    [request setEntity:entity];
    
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"key=%@", key];
    [request setPredicate:predicate];
    
    NSError *error;
    NSArray *resultData = [dataManager.managedObjectContext executeFetchRequest:request
                                                                          error:&error];
    
    if (kArrayIsEmpty(resultData)) {// Insert new obj to entity
        NSLog(@"CoreData --- Insert new obj entity --- %@", EntityName);
        
        User *userEntity = [NSEntityDescription insertNewObjectForEntityForName:EntityName
                                                        inManagedObjectContext:dataManager.managedObjectContext];
        userEntity.imei = [NSString stringWithFormat:@"%@", [dataSource objectForKey:@"imei"]];
        userEntity.userType = [NSString stringWithFormat:@"%@", [dataSource objectForKey:@"userType"]];
        userEntity.project = [NSString stringWithFormat:@"%@", [dataSource objectForKey:@"project"]];
        
    } else {// Update current entity operation
        NSLog(@"CoreData --- Update current entity operation --- %@", EntityName);
        
        for (User *userEntity in resultData) {
            if ([userEntity.key isEqualToString:key]) {
                userEntity.imei = [NSString stringWithFormat:@"%@", [dataSource objectForKey:@"imei"]];
                userEntity.userType = [NSString stringWithFormat:@"%@", [dataSource objectForKey:@"userType"]];
                userEntity.project = [NSString stringWithFormat:@"%@", [dataSource objectForKey:@"project"]];
            }
        }
    }
    
    if (error) {
        NSLog(@"****** CoreData Error - [%@] insert obj for entity ******\n%@", EntityName, error);
    }
    
    // Save processing result
    BOOL saveState = [dataManager.managedObjectContext save:&error];
    // Callback result state
    if (result) {
        result(saveState, error);
    }
}

通过如上 code 的对比，心细的大家应该发现了问题的所在，事后排查完问题的所在，发现自己当时好！@#￥%，因为 for in 遍历数据的时候一个数据源的错误导致了这个异常问题。。。

// 如下遍历的数据源应该是数据库查询结果后的 resultData，而非方法传参的数据库 。。。 大意啊大意！
for (User *userEntity in resultData) {
    if ([userEntity.key isEqualToString:key]) {
        userEntity.imei = [NSString stringWithFormat:@"%@", [dataSource objectForKey:@"imei"]];
        userEntity.userType = [NSString stringWithFormat:@"%@", [dataSource objectForKey:@"userType"]];
        userEntity.project = [NSString stringWithFormat:@"%@", [dataSource objectForKey:@"project"]];
    }
}

不过异常虽小，但汤过坑也算给往后长个记性，更加的细心吧！

以上便是此次分享的内容,希望内容能对大家实际有所帮助,有什么不足之处欢迎指点共同进步!