Function parameter in swift to accept array or string

Question

I want to write a function named remove in Swift which will accept an array or a string and remove the string from a dictionary if it is a string else it will remove all the strings from the dictionary which are present in the array. Also, this function that I wrote is disabling the styles in the editor of Xcode.

func remove(key: AnyObject){
    if key is Array{
        for (index, value) in enumerate(key){
            if -1 < self._getDataStoreKeyIndex(value){
               self._removeProperty(value)
            } else{
                self._removeItem(value)
            }
        }
    }else{
        if -1 < self._getDataStoreKeyIndex(key){
           self._removeProperty(key)
        }else{
            self._removeItem(key)
       }
    }
}

The other functions in the code are correct because if I comment this function my project is building successfully. What is wrong in my code?

I am getting a segmentation fault.

<unknown>:0: error: unable to execute command: Segmentation fault: 11

You need to give more details... what's not working? bad result? exception? — Antonio
– Antonio, Commented Aug 26, 2014 at 12:34
Set a breakpoint at the beginning of the function then step through the code to see exactly where it crashes. — zisoft
– zisoft, Commented Aug 26, 2014 at 12:43

David Berry · Accepted Answer · 2014-08-26 19:19:41Z

The heart of the problem is attempting to convert to "Array" which is a generic class. Instead, you need to convert to a specific instantiation of the generic, in your case "Array" or "[String]"

You also have a problem in that you can't enumerate AnyObject, combined, you need something like:

func remove(key: AnyObject) {
    if let array = key as? Array<String> {
        for (index, value) in enumerate(array) {
        }
    }
    else {
    }
}

Although I'm not sure why you're using enumerate to get at the indices which you don't use for anything, faster and more legible to just iterate the array directly:

func remove(key: AnyObject) {
    if let array = key as? Array<String> {
        for value in array {
        }
    }
    else {
    }
}

One further thought... these two operations really aren't similar and don't really share much code. Why not define to different functions that differ in signature:

func remove(key:String) {
}

func remove(array:[String]) {
    for string in array {
        remove[string]
    }
}

Which eliminates the possibility that somebody calls "remove(5)"

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