Generally speaking, you have unitary methods (like saveRecord), which deal with only one record at a time, and mass operations (like CKModifyRecordsOperation), which deal with several records at the same time.
These save operations can be used to save records, or to update records (that is, fetch them, apply changes to them, and then save them again).
SAVE examples:
You create a record and want to save it to CloudKit DB:
let database = CKContainer.defaultContainer().publicCloudDatabase
var record = CKRecord(recordType: "YourRecordType")
database.saveRecord(record, completionHandler: { (savedRecord, saveError in
if saveError != nil {
println("Error saving record: \(saveError.localizedDescription)")
} else {
println("Successfully saved record!")
}
})
You create a bunch of records and you want to save them all at once:
let database = CKContainer.defaultContainer().publicCloudDatabase
// just an example of how you could create an array of CKRecord
// this "map" method in Swift is so useful
var records = anArrayOfObjectsConvertibleToRecords.map { $0.recordFromObject }
var uploadOperation = CKModifyRecordsOperation(recordsToSave: records, recordIDsToDelete: nil)
uploadOperation.savePolicy = .IfServerRecordUnchanged // default
uploadOperation.modifyRecordsCompletionBlock = { savedRecords, deletedRecordsIDs, error in
if error != nil {
println("Error saving records: \(error.localizedDescription)")
} else {
println("Successfully saved records")
}
}
database.addOperation(uploadOperation)
UPDATE examples:
Usually, you have 3 cases in which you want to update records :
- you know the record identifier (generally the recordID.recordName of the record you want to save: in that case,
you will use methods fetchRecordWithID and then saveRecord
you know there is a unique record to update but you don't know its recordID: in that case, you will use a query with method
performQuery, select the (only) one you need and again saveRecord
you are dealing with many records that you want to update: in that case, you will use a query to fetch them all
(performQuery), and a CKModifyRecordsOperation to save them all.
Case 1 - you know the unique identifier for the record you want to update:
let myRecordName = aUniqueIdentifierForMyRecord
let recordID = CKRecordID(recordName: myRecordName)
database.fetchRecordWithID(recordID, completionHandler: { (record, error) in
if error != nil {
println("Error fetching record: \(error.localizedDescription)")
} else {
// Now you have grabbed your existing record from iCloud
// Apply whatever changes you want
record.setObject(aValue, forKey: attributeToChange)
// Save this record again
database.saveRecord(record, completionHandler: { (savedRecord, saveError) in
if saveError != nil {
println("Error saving record: \(saveError.localizedDescription)")
} else {
println("Successfully updated record!")
}
})
}
})
Case 2 - you know there is a record corresponding to your conditions, and you want to update it:
let predicate = yourPredicate // better be accurate to get only the record you need
var query = CKQuery(recordType: YourRecordType, predicate: predicate)
database.performQuery(query, inZoneWithID: nil, completionHandler: { (records, error) in
if error != nil {
println("Error querying records: \(error.localizedDescription)")
} else {
if records.count > 0 {
let record = records.first as! CKRecord
// Now you have grabbed your existing record from iCloud
// Apply whatever changes you want
record.setObject(aValue, forKey: attributeToChange)
// Save this record again
database.saveRecord(record, completionHandler: { (savedRecord, saveError in
if saveError != nil {
println("Error saving record: \(saveError.localizedDescription)")
} else {
println("Successfully updated record!")
}
})
}
}
})
Case 3 - you want to grab multiple records, and update them all at once:
let predicate = yourPredicate // can be NSPredicate(value: true) if you want them all
var query = CKQuery(recordType: YourRecordType, predicate: predicate)
database.performQuery(query, inZoneWithID: nil, completionHandler: { (records, error) in
if error != nil {
println("Error querying records: \(error.localizedDescription)")
} else {
// Now you have grabbed an array of CKRecord from iCloud
// Apply whatever changes you want
for record in records {
record.setObject(aValue, forKey: attributeToChange)
}
// Save all the records in one batch
var saveOperation = CKModifyRecordsOperation(recordsToSave: records, recordIDsToDelete: nil)
saveOperation.savePolicy = .IfServerRecordUnchanged // default
saveOperation.modifyRecordsCompletionBlock = { savedRecords, deletedRecordsIDs, error in
if error != nil {
println("Error saving records: \(error.localizedDescription)")
} else {
println("Successfully updated all the records")
}
}
database.addOperation(saveOperation)
}
})
Now, that was a lenghty answer to your question, but your code mixed both a unitary save method with a CKModifyRecordsOperation.
Also, you have to understand that, each time you create a CKRecord, CloudKit will give it a unique identifier (the record.recordID.recordName), unless you provide one yourself. So you have to know if you want to fetch an existing record, or create a new one before calling all these beautiful methods :-)
If you try to create a new CKRecord using the same unique identifier as another one, then you'll most certainly get an error.