Extra argument 'error' in call - do/catch? - swift

Question

I know there is new error handling i.e. do/catch but not sure if it applies here and even if it does it's pretty difficult for me even going through the documentation. Could someone show me the correct code block please.
/*** error Extra argument 'error' in call ***/
var plistDic = NSPropertyListSerialization.propertyListWithData(plistData!,
options:Int(NSPropertyListMutabilityOptions.MutableContainersAndLeaves.rawValue),
format: nil, error: &error) as Dictionary<String, Dictionary<String, String>>
assert(error == nil, "Can not read data from the plist")
return plistDic
}
// END
EDIT:
let YALCityName = "name"
let YALCityText = "text"
let YALCityPicture = "picture"
private let kCitiesSourcePlist = "Cities"
class YALCity: Equatable {
var name: String
var text: String
var image: UIImage
var identifier: String
// MARK: Class methods
class internal func defaultContent() -> Dictionary<String, Dictionary<String, String>> {
let path = NSBundle.mainBundle().pathForResource(kCitiesSourcePlist, ofType: "plist")
let plistData = NSData(contentsOfFile: path!)
assert(plistData != nil, "Source doesn't exist")
do {
let plistDic = try NSPropertyListSerialization.propertyListWithData(plistData!,
options:NSPropertyListMutabilityOptions.MutableContainersAndLeaves,
format: nil
)
if let dictionary = plistDic as? Dictionary< String, Dictionary<String, String> > {
print("\(dictionary)")
}
else {
print("Houston we have a problem")
}
}
catch let error as NSError {
print(error)
}
return defaultContent()
}
init(record:CKRecord) {
self.name = record.valueForKey(YALCityName) as! String
self.text = record.valueForKey(YALCityText) as! String
let imageData = record.valueForKey(YALCityPicture) as! NSData
self.image = UIImage(data:imageData)!
self.identifier = record.recordID.recordName
}
}
func ==(lhs: YALCity, rhs: YALCity) -> Bool {
return lhs.identifier == rhs.identifier
}

Answer 1

Try this code:
do {
var plistDic = try NSPropertyListSerialization.propertyListWithData(plistData!,
options:NSPropertyListMutabilityOptions.MutableContainersAndLeaves,
format: nil
)
// plistDic is of type 'AnyObject'. We need to cast it to the
// appropriate dictionary type before using it.
if let dictionary = plistDic as? Dictionary<String, Dictionary<String, String>> {
// You are good to go.
// Insert here your code that uses dictionary (otherwise
// the compiler will complain about unused variables).
// change 'let' for 'var' if you plan to modify the dictionary's
// contents.
// (...)
}
else {
// Cast to dictionary failed: plistDic is NOT a Dictionary with
// the structure: Dictionary<String, Dictionary<String, String>>
// It is either a dictionary of a different internal structure,
// or not a dictionary at all.
}
}
catch let error as NSError {
// Deserialization failed (see console for details:)
print(error)
}
Note: I split the call to a function that throws (try...) and the casting to your specific type of Dictionary (if let...) because I'm not really sure exactly what would happen if the call succeeds but the cast fails, or if it would be clear which one failed from the debugger. Also, I don't like too many things happening in one line...
EDIT: I fixed the options parameter. In Swift, Ints and enums aren't interchangeable; you need to pass the right type (I missed it the first time when modifying your code).