Snippets

Collection of code snippets, extensions, etc. I have found useful and future-me may want to use as well.

UIResponder 'identifier' Extension

This simple extension returns the stringified Class name on all sub-classes of UIResponder. Which is a bunch, including UIViewController, UIView, and many more.

extension UIResponder {
    static var identifier : String {
        return String(describing: self)
    }
}

Example

Leverages autocomplete to cut out a lot of repetive typing. And typos. Typos suck.

if segue.identifier == "MyCustomViewController"

in every prepareForSegue becomes:

if segue.identifier == MyCustomViewController.identifier

Doesn't look much shorter, but with autocomplete, MUCH quicker. And more accurate.

PropertyNames Protocol/Extension

This protocol and conforming extension will (generally) return a list of the Swift object's property names as an array of Strings. I stumbled across while trying to re-factor my CloudKit Record constructor methods. It bothered me to repeatedly pass in Keys as String, because DRY and Strings are prone to typos. Typos suck. Also, use of flatMap removes need for optional unwrapping.

protocol PropertyNames {
    func propertyNames() -> [String]
}

extension PropertyNames {
    func propertyNames() -> [String] {
        return Mirror(reflecting: self).children.flatMap { $0.label }
    }
}

Example

In my TimeClock app, creating a CloudKit Record from a Location instance went from:

func createCKRecordFrom(location: Location) -> CKRecord? {
        let locationRecord = CKRecord(recordType: "Location")
        locationRecord["displayName"] = location.displayName as? CKRecordValue
        locationRecord["id"] = location.id as? CKRecordValue
        locationRecord["billableRate"] = location.rate as? CKRecordValue
        locationRecord["isEnabled"] = location.isEnabled as? CKRecordValue
        if let address = location.address {
            locationRecord["address"] = address as? CKRecordValue
        }
        if let city = location.city {
            locationRecord["city"] = city as? CKRecordValue
        }
        if let state = location.state {
            locationRecord["state"] = state as? CKRecordValue
        }
        if let zipCode = location.zipCode {
            locationRecord["zipCode"] = zipCode as? CKRecordValue
        }
        return locationRecord

to

func makeCKRecordFrom(location: Location) -> CKRecord {
    let locationRecord = CKRecord(recordType: location.identifier)
    location.propertyNames().flatMap { locationRecord[$0] = location.value(forKey: $0) as? CKRecordValue }
    return locationRecord
}

Concise and accurate.
NOTE: value(forKey:) on line 54 works because Location conforms to NSObject (for NSCoding purposes.)
H/T to NSHipster for another great discussion/explanation:
http://nshipster.com/mirrortype/