Objective c 将核心数据值放入数组中
我需要将使用从核心数据图获取请求检索到的值放入数组中,但不完全确定如何执行此操作 我正在使用以下命令执行提取:Objective c 将核心数据值放入数组中,objective-c,ios,uitableview,core-data,Objective C,Ios,Uitableview,Core Data,我需要将使用从核心数据图获取请求检索到的值放入数组中,但不完全确定如何执行此操作 我正在使用以下命令执行提取: NSString *entityName = @"Project"; // Put your entity name here NSLog(@"Setting up a Fetched Results Controller for the Entity named %@", entityName); // 2 - Request that En
NSString *entityName = @"Project"; // Put your entity name here
NSLog(@"Setting up a Fetched Results Controller for the Entity named %@", entityName);
// 2 - Request that Entity
NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:entityName];
// 3 - Filter it if you want
request.predicate = [NSPredicate predicateWithFormat:@"belongsToProject = %@", _selectedProject];
// 4 - Sort it if you want
request.sortDescriptors = [NSArray arrayWithObject:[NSSortDescriptor sortDescriptorWithKey:@"dateTaken"
ascending:YES
selector:@selector(localizedCaseInsensitiveCompare:)]];
// 5 - Fetch it
self.fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:request
managedObjectContext:self.managedObjectContext
sectionNameKeyPath:nil
cacheName:nil];
[self performFetch];
如您所见,我正在使用NSPredicate筛选返回的值
如何将这些值放入数组中,并在它们位于数组中后为实体选择单个属性,例如project.description或project.name
多亏了Eimantas,我在一个数组中获得了对象,但是我仍然需要做两件事:
for (int i=0; i < [projectListArray count]; i++)
{
NSString *tmp = (NSString *)[projectListArray objectAtIndex:i];
}
似乎我没有递增?
[self.fetchedResultsController fetchedObject]
返回已获取对象的数组
更新
最好使用快速枚举,而不是for
循环:
for (Project *project in projectListArray) {
NSString *projectDescription = [project valueForKey:@"description"];
}
您之所以会出现异常,是因为您正在将对象强制转换为
NSString
,而它是指向(我猜想)项目的指针。非常棒,谢谢您Eimantas。如果你不介意帮忙的话,我还有一件事要做?我已经更新了我原来的问题。
for (Project *project in projectListArray) {
NSString *projectDescription = [project valueForKey:@"description"];
}