Error fetching: Error Domain=NSCocoaErrorDomain Code=134060
"The operation couldn’t be completed. (Cocoa error 134060.)"
UserInfo=0x132eb960 {reason=The fetched object at index 76
has an out of order section name 'å. Objects must be sorted by section name'}
我检查了一下,还有其他同名的问题,但是在本例
我很好奇创建Fetch Request模板与以编程方式创建NSFetchRequest相比是否会提高性能,所以我写了一些测试来衡量这一点。。
模拟器和iPhone (测量执行大量获取的时间间隔)的差异顺序相同:
just creating an NSFetchRequest: 4.399674
creating a Fetch Request Template: 0.501369
NSFetchRequest with field indexed: 0.407068
Fetch Request Template and field indexed:
我必须为我的NSFetchRequest应用程序创建一个iPhone,它返回与以下iPhone语句相同的结果:
SELECT week
, year
, SUM(duration) AS totalDuration
FROM myTable
GROUP BY year
, week
我试图用以下代码来解决这个问题:
NSExpression * durationExpression = [NSExpression expressionForFunction:@"sum:" arguments:[NSArray arrayWithObject:
如果我的核心数据中有三个实体,它们都有一对多的关系:
extension Progress {
@nonobjc public class func createFetchRequest() -> NSFetchRequest<Progress> {
return NSFetchRequest<Progress>(entityName: "Progress")
}
@NSManaged public var goal: Goal
@NSManaged public var metric: Set&
我尝试为实体NSFetchRequest设置一个country和city等属性的实体
country | city
————————————————
Germany | Berlin
USA | San Francisco
USA | New York
Germany | Munich
Germany | Munich
USA | San Francisco
Germany | Stuttgart
NSFetchRequest应该返回国家(或带有适当国家的位置对象)和城市数量。
[
{ country: 'Germany', ci
我想使用CHCSVParser将我的核心数据导出到CSV。我知道如何从entity获取所有值,但我不知道如何写入CSV。
有人能教我如何用CHCSVParser写CSV吗?
// Test listing all Infos from the store
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription
entityForName:@"NoteLog
我在这本书的帮助下学习核心数据。这里有一个代码:
- (void)loadData {
// Pull the movies. If we have 200, assume our db is set up.
NSManagedObjectContext *context = [self managedObjectContext];
NSFetchRequest *request = [[NSFetchRequest alloc] init];
[request setEntity:[NSEntityDescription entityForName:@"Movie"