Segmentation Fault while reading JSON parse to NSArray in swift - ios

Question

There is a method used to fill realm database from json:
func parseJSON(data: NSData) -> NSArray? {
do {
let array: NSArray = try NSJSONSerialization.JSONObjectWithData(data, options: .MutableContainers) as! NSArray
return array
} catch _ {
return nil
}
}
//parameter came from previous method
func updateDatabaseFromParsedJson(parsedJson: NSArray) {
let realm = try! Realm()
try! realm.write {
realm.deleteAll()
}
for i in 0..<parsedJson.count {
let deviceObject = parsedJson[i]
let name = deviceObject["name"] as! String
let id = deviceObject["id"] as! Int
var device = Device()
device.name = name
device.id = id
try! realm.write {
realm.add(device)
}
var deviceMeasuresArray = deviceObject["measures"] as! NSArray
for i in 0..<deviceMeasuresArray.count {
var measureObject = deviceMeasuresArray[i]
var measure = Measure()
measure.slug = measureObject["name"]
measure.device = device
measure.localize()
try! realm.write {
realm.add(measure)
}
var measureEntriesArray = measureObject["averages"] as! NSArray
for i in 0..<measureEntriesArray.count {
var entryObject = measureEntriesArray[i]
var entry = PeriodAverage()
entry.measure = measure
entry.value = entryObject["value"]
entry.start = NSDate.parse(entryObject["start"])
entry.end = NSDate.parse(entryObject["end"])
entry.length = entryObject["length"]
try! realm.write {
realm.add(entry)
}
}
}
}
}
extension NSDate {
class func parse(dateString: String) -> NSDate {
let format = "yyyy-MM-dd'T'HH:mm:ss'Z'"
let formatter = NSDateFormatter()
formatter.dateFormat = format
return formatter.dateFromString(dateString)!
}
}
JSON itself http://188.166.51.200/api/v1/actual_data/
While compiling I get error Error:unable to execute command: Segmentation fault: 11
Where I am wrong and how to properly parse my json? I think problem is in lines where json fields forcely parsed to objects but I am new in swift and can't exactly determine the error.

Answer 1

You've apparently run across a compiler issue (which you should report to Apple), although it's easy enough to work around. If you're using Swift you should really be using Swift collection types instead Foundation collection types if possible (i.e., Array instead of NSArray) which allow for more type information. Also, while you're casting some of the values you're getting out of your JSON, you're not casting them all. Adding this additional type information will make the compiler behave and work around the issue. I would suggest the following edit:
func updateDatabaseFromParsedJson(parsedJson: Array<AnyObject>) {
let realm = try! Realm()
try! realm.write {
realm.deleteAll()
}
for i in 0..<parsedJson.count {
let deviceObject = parsedJson[i] as! Dictionary<String, AnyObject>
let name = deviceObject["name"] as! String
let id = deviceObject["id"] as! Int
var device = Device()
device.name = name
device.id = id
try! realm.write {
realm.add(device)
}
var deviceMeasuresArray = deviceObject["measures"] as! Array<AnyObject>
for i in 0..<deviceMeasuresArray.count {
var measureObject = deviceMeasuresArray[i] as! Dictionary<String, AnyObject>
var measure = Measure()
measure.slug = measureObject["name"] as! String // I'm guessing on the type here
measure.device = device
measure.localize()
try! realm.write {
realm.add(measure)
}
var measureEntriesArray = measureObject["averages"] as! Array<AnyObject>
for i in 0..<measureEntriesArray.count {
var entryObject = measureEntriesArray[i] as! Dictionary<String, AnyObject>
var entry = PeriodAverage()
entry.measure = measure
entry.value = entryObject["value"] as! String // Guessing on the type here also
entry.start = NSDate.parse(entryObject["start"] as! String)
entry.end = NSDate.parse(entryObject["end"] as! String)
entry.length = entryObject["length"] as! String // Again, guessing on the type here
try! realm.write {
realm.add(entry)
}
}
}
}
}
Unrelated to the compiler issue, you could also use for-in loops to make your code more Swift like. You can read more about them in the For-In Loops section of the Control Flow chapter of The Swift Programming Language.