how I can call es request with distinct values in swift?
This is my code:
let appDelegate: AppDelegate = UIApplication.sharedApplication().delegate as AppDelegate
let context: NSManagedObjectContext = appDelegate.managedObjectContext
let request = NSFetchRequest(entityName: "MedicalData")
request.propertiesToFetch = NSArray(object: "docID")
request.returnsObjectsAsFaults = false
request.returnsDistinctResults = true
var results:NSArray = context.executeFetchRequest(request, error: nil)
for data in results {
var thisData = data as MedicalData
println(thisData.docID)
}
I want to get distinct values for "docID" but I get all of the entity :(
Thank your for help!
You need to set
request.resultType = NSFetchRequestResultType.DictionaryResultType
It returns dictionaries, but the distinct filter should work.
If you do not want to go down that route, filter in memory (also recommended). Do a normal fetch and then
let distinct = NSSet(array: results.valueForKeyPath("docID") as [String])
With Swift 2.0 I prefer
let distinct = NSSet(array: results.map { $0.docID })
As already mentioned the key is using
fetchRequest.resultType = NSFetchRequestResultType.DictionaryResultType
and
fetchRequest.propertiesToFetch = ["propertyName"]
both are required for distinct to work
fetchRequest.returnsDistinctResults = true
The next step is to deal with the results as Swift Dictionaries and returning the wanted values.
let appDelegate = UIApplication.sharedApplication().delegate as AppDelegate
let managedContext = appDelegate.managedObjectContext!
//FetchRequest
let fetchRequest = NSFetchRequest(entityName: "Purchase")
fetchRequest.propertiesToFetch = ["year"]
fetchRequest.resultType = NSFetchRequestResultType.DictionaryResultType
fetchRequest.returnsDistinctResults = true
//Fetch
var error: NSError?
if let results = managedContext.executeFetchRequest(fetchRequest, error: &error) {
var stringResultsArray: [String] = []
for var i = 0; i < results.count; i++ {
if let dic = (results[i] as? [String : String]){
if let yearString = dic["year"]?{
stringResultsArray.append(yearString)
}
}
}
return stringResultsArray
}else {
println("fetch failed: \(error?.localizedDescription)")
}
return []
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With