CODEWITHSUNDEEP
iosarraysswiftdictionarynull
Lance Samaria
Lance Samaria

Reputation: 19592

Swift iOS -Get dictionary to accept nil value

I have an array that can hold up to 4 values. The array will always have at least 1 value but the other 3 may be nil. I have to take the elements inside the array and assign them to class properties.

The problem is once I iterate through the array, get nil values, assign them to the class properties and then try to assign those nil properties to my dictionary, I get a crash.

I need the dictionary to accept the values with colors and ignore the nil values. So I have 2 problems.

  1. The colors from the array that do exist are coming up as nil in myDict
  2. The nil values in the array are exceptions

How would I go about fixing this?

code:

class ColorClass{
    var colorOne:String?
    var colorTwo:String?
    var colorThree:String?
    var colorFour:String?
}

let colorClass = ColorClass()
var randColors: [String?] = []

//In this case I have 2 colors but sometimes randColors may have 1 color or 3 colors or 4 colors. It will always vary
randColors = ["purple","pink"]

for (index,element) in randColors.enumerate(){

    switch index {
    case 0:
        if let elZero = element{
            colorClass.colorOne = elZero
        }
    case 1:
        if let elOne = element{
            colorClass.colorTwo = elOne
        }
    case 2:
        if let elTwo = element{
            colorClass.colorThree = elTwo
        }
    case 3:
        if let elThree = element{
            colorClass.colorFour = elThree
        }
    default:
        break
    }
}

var myDict = [String:AnyObject]()
myDict.updateValue(colorClass.colorOne!, forKey: "firstKey")
myDict.updateValue(colorClass.colorTwo!, forKey: "secondKey")
myDict.updateValue(colorClass.colorThree!, forKey: "thirdKey")
myDict.updateValue(colorClass.colorFour!, forKey: "fourthKey")

The crashes occur on:

myDict.updateValue(colorClass.colorThree!, forKey: "thirdKey")
myDict.updateValue(colorClass.colorFour!, forKey: "fourthKey")

Upvotes: 1

Views: 507

Answers (1)

Hitendra Solanki
Hitendra Solanki

Reputation: 4941

Use if let to ignore nil values while adding/updating the values in the dictionary.

if let clrThree = colorClass.colorThree {
     myDict.updateValue(clrThree, forKey: "thirdKey")
}

if let clrFour = colorClass.colorFour {
     myDict.updateValue(clrFour, forKey: "fourthKey")
}

Reason of Crashes is, you are using ! after the colorClass.colorFour i.e. you are using as colorClass.colorFour!.

When swift finds the value of the variable as nil and try to forcefully unwrap it the application will crash unexpectedly found nil while unwrapping

Upvotes: 2

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