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swiftxcodecore-dataoption-typeint32

Optional Int32 values in Core Data require unwrapping of optional Int32 values in code

In Core Data, attributes of type String and Int32 are "Optional" (ticked in properties).

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Corresponding to these values in code, are the same types as optionals.

        var color1: String?
        var color2: String?
        var color3: String?
        var colorRangeLoc1: Int32?
        var colorRangeLoc2: Int32?
        var colorRangeLoc3: Int32?

Values are set in some cases, and passed to a function, as optionals, for transfer to Core Data.

func loadCellData(text: String, sortOrder: Int32, portion: Float, color1: String?, color2: String?, color3: String?, colorRangeLoc1: Int32?, colorRangeLoc2: Int32?, colorRangeLoc3: Int32?, colorRangeLen1: Int32?, colorRangeLen2: Int32?, colorRangeLen3: Int32?, underlineRangeLoc1: Int32?, underlineRangeLoc2: Int32?, underlineRangeLoc3: Int32?, underlineRangeLen1: Int32?, underlineRangeLen2: Int32?, underlineRangeLen3: Int32?)
{
    let appDelegate = UIApplication.shared.delegate as! AppDelegate
    let context = appDelegate.persistentContainer.viewContext

    let entry: CellData = NSEntityDescription.insertNewObject(forEntityName: "CellData", into: context) as! CellData

    entry.text = text
    entry.sortOrder = sortOrder
    entry.portion = portion
    entry.color1 = color1
    entry.color2 = color2
    entry.color3 = color3
    entry.colorRange1Loc = colorRangeLoc1
    entry.colorRange2Loc = colorRangeLoc2
    entry.colorRange3Loc = colorRangeLoc3
...

Xcode compiles without error for the String? values, color1, color2 and color3, but shows the following error for Int32? values:

Value of optional type 'Int32?' must be unwrapped to a value of type 'Int32'

This suggests that the optional Int32 in CoreData is demanding an unwrapped optional value (while the optional Strings are fine)? Is there a difference (it would help me to understand why), and if so how is it best managed?

Assigning 'nil' as a starting value does not work. Force unwrapping causes a crash if nil (of course). Is it necessary to check for all values of type Int32?

if colorRangeLoc1 != nil { entry.colorRangeLoc1 = colorRangeLoc1 }

Or should it be 'guard' or 'if let'?

Solution

  • Optional values in CoreData are not the same as in Swift. As per the comments, for numbers at least, set a mandatory - impossible value - instead of nil, and check this when using the value.