avoid repeating code in swift 4

Question

I would like to create a generic function to avoid repeating while using conditions. Is there any possible ideas to achieve this? Thanks

struct ObjectDataItem {
var name: String
var value: String
}

static func arrayFields(arrayObject: ArrayObject) -> Array<ObjectDataItem> {
    var objectFields = [ObjectDataItem]()

    if let objectCategoryValue = arrayObject.objectCategory {
        let data = [ObjectDataItem(name: ObjectCategoryConstant.objectCategoryKey, value: objectCategory)]
        objectFields.append(contentsOf: data)
    }

    if let objectTypeValue = arrayObject.objectType {
        let data = [ObjectDataItem(name: ObjectTypeConstant.objectTypeKey, value: objectTypeValue)]
        objectFields.append(contentsOf: data)
    }

    if let objectName = arrayObject.objectName {
        let data = [ObjectDataItem(name: ObjectNameConstant.objectNameKey, value: objectName)]
        objectFields.append(contentsOf: data)
    }

    if let countryObjectValue = arrayObject.countryObjectCode {
        let data = [ObjectDataItem(name: countryObjectConstant.countryObjectCodeKey, value: countryObjectValue)]
        objectFields.append(contentsOf: data)
    }

    return objectFields
}

What are the methods `. objectCategoryKey` which are put on `String`? — Sulthan, Mar 06 '18 at 07:05
Why don't you use a normal `objectFields.append(ObjectDataItem(...))`? Actually you have almost no duplicate code. The code you be probably simplified by changing your data representation. Which is not included in you question. — Sulthan, Mar 06 '18 at 07:06
Humm i thought maybe i can have generic func somehow to reduce this if contidions repeading.. @Sulthan — dicle, Mar 06 '18 at 07:10

score 1 · Accepted Answer · answered Mar 06 '18 at 09:31

You could use keypaths

func arrayFields(arrayObject: ArrayObject) -> Array<ObjectDataItem> {
    var objectFields = [ObjectDataItem]()

    func appendField(key: String, valuePath: KeyPath<ArrayObject, String?>) {
        if let value = arrayObject[keyPath: valuePath] {
            let data = [ObjectDataItem(name: key, value: value)]
            objectFields.append(contentsOf: data)
        }
    }

    appendField(key: ObjectCategoryConstant.objectCategoryKey, valuePath: \ArrayObject.objectCategory)
    appendField(key: ObjectCategoryConstant.objectTypeKey, valuePath: \ArrayObject.objectType)

    return objectFields
}

You could go a step further and use a dictionary to lookup the keys, so in the end you would only have to pass in the keypath.

score 0 · Answer 2 · answered Mar 06 '18 at 07:16

The only thing that makes sense to me is to create a dictionary first:

var dataDictionary: [String: String] = [:]
dataDictionary[ObjectCategoryConstant.objectCategoryKey] = arrayObject.objectCategory
dataDictionary[ObjectCategoryConstant.objectTypeKey] = arrayObject.objectType
dataDictionary[ObjectCategoryConstant.objectNameKey] = arrayObject.objectName
dataDictionary[countryObjectConstant.countryObjectCodeKey] = arrayObject.countryObjectValue

let objectFields = dataDictionary.map { (name, value) in
    ObjectDataItem(name: name, value: countryObjectValue)
}

Dictionary does not contain values that are nil. However, you lose the ordering of values (if it's important for you). The simplification is not very big either.

also in this way again i need to type "ObjectDataItem(name: name, value: arrayObject .countryObjectValue)" this for all .. humm yeah simplification is not big.. — dicle, Mar 06 '18 at 07:32

score 0 · Answer 3 · answered Mar 06 '18 at 07:35

You can also use reflection if you do not mind your keys to be the names of your property names Something like this:

func arrayFields(arrayObject: ArrayObject) -> Array<ObjectDataItem> {
    var objectFields = [ObjectDataItem]()
    let objectMirror = Mirror(reflecting: arrayObject)
    for child in objectMirror.children {
        let (propertyName, propertyValue) = child
        objectFields.append(ObjectDataItem(name:propertyName!, value: propertyValue as! String))
    }
    return objectFields
}

avoid repeating code in swift 4

3 Answers3