Question

core data怎么统计总数

比如说有这样一个表type count1 52 52 5我想得到 type=2 的count都相加 得到一个结果就可core data 要怎么做，请高手指教。

Answer 1

我刚开始跟着老头学iOS开发，他的做法似乎是这样的：NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName: @"XXX"]; request.predicate = [NSPredicate predicateWithFormat:@"type= %@"，@“2”]; NSSortDescriptor *sortDescriptor = [NSSortDescriptor sortDescriptorWithKey: @"XXXX" ascending:YES]; request.sortDescriptors = [NSArray arrayWithObject:sortDescriptor]; NSError *error = nil; NSArray *match = [context executeFetchRequest:request error:&error];这样得

Answer 2

Swift版本的：

// 获取Context
func getContext () -> NSManagedObjectContext {
    let appDelegate = UIApplication.shared.delegate as! AppDelegate
    return appDelegate.persistentContainer.viewContext
}
func getHowManyDataIn(theNameOfYourEntity:String){
    // getContext()
    let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: theNameOfYourEntity)
    do {
        let searchResults = try getContext().fetch(fetchRequest)
        print("numbers of \(searchResults.count)")
    } catch  {
        print(error)
    }
}