What is Extension:
Extensions are basically similar to an Objective-C category. Extensions are sort of methods adding in a Classe or Structure in a different flavour.
Syntax of Extension:
The syntax to create an extension is very similar to creating a type. You can write the following code in your Utils.swift class to add a UIColor extension.
extension UIColor
{
//Fill in the blank
}
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Common Extensions List:
NSData Extensions:
//MARK: NSData Extensions
extension NSData {
// Convert Data to HexString mostly used in Encrypton Algos
public var hexString: String {
return self.toHexString()
}
func toHexString() -> String {
let count = self.length / sizeof(UInt8)
var bytesArray = [UInt8](count: count, repeatedValue: 0)
self.getBytes(&bytesArray, length:count * sizeof(UInt8))
var s:String = "";
for byte in bytesArray {
s = s + String(format:"%02X", byte)
}
return s;
}
// Return Swift Array from NSData
public func arrayOfBytes() -> [UInt8] {
let count = self.length / sizeof(UInt8)
var bytesArray = [UInt8](count: count, repeatedValue: 0)
self.getBytes(&bytesArray, length:count * sizeof(UInt8))
return bytesArray
}
// Return array from NSData
class public func withBytes(bytes: [UInt8]) -> NSData {
return NSData(bytes: bytes, length: bytes.count)
}
}
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Note: NSData has an initializer that looks takes a bytes pointer: init(bytes: UnsafeMutablePointer , length: Int).
You can read more about unsafe pointer parameters in Apple’s Interacting with C APIs
NSFileManager Extensions:
//MARK: NSFileManager Extensions
extension NSFileManager {
class func documentsDirectory() -> String {
var paths = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true) as! [String]
return paths[0]
}
class func cachesDirectory() -> String {
var paths = NSSearchPathForDirectoriesInDomains(.CachesDirectory, .UserDomainMask, true) as! [String]
return paths[0]
}
}
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Array Extensions:
//MARK: Array Extensions
extension Array {
//Array First Object
func firstObject() -> T! {
var firstItem: T!
if !self.isEmpty {
firstItem = self[0]
}
return firstItem
}
//Array Last Object
func lastObject() -> T! {
var lastItem: T!
if !self.isEmpty {
lastItem = self[self.count-1]
}
return lastItem
}
// Remove Object from Array similar to [ArrayObjec removeObject:(id)] in Objective-C
mutating func removeObject(object: U) -> Bool {
for (idx, objectToCompare) in enumerate(self) {
if let to = objectToCompare as? U {
if object == to {
self.removeAtIndex(idx)
return true
}
}
}
return false
}
// Check Array contains Object similar to [ArrayObjec containsObject:(id)] in Objective-C
func contains(obj: T) -> Bool {
return self.filter({$0 as? T == obj}).count > 0
}
}
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NSObject Extensions:
// Perform selector after delay in swift
extension NSObject {
func callSelectorAsync(selector: Selector, object: AnyObject?, delay: NSTimeInterval) -> NSTimer {
var timer = NSTimer.scheduledTimerWithTimeInterval(delay, target: self, selector: selector, userInfo: object, repeats: false)
return timer
}
}
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Localization String Extensions:
// localized string extension
extension String {
var localized: String {
return NSLocalizedString(self, tableName:nil, bundle: NSBundle.mainBundle(), value: self, comment: "")
}
}
// localizing String with comment
extension String{
func localizedStringWithComment(comment:String)-> String{
return NSLocalizedString(self, tableName: nil, bundle: NSBundle.mainBundle(), value: self, comment: comment)
}
}
extension String{
// MARK: Remove White Spaces
var condenseWhitespace:String{
return self.stringByReplacingOccurrencesOfString(" ", withString: "")
}
}
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Integer Extensions:
// MARK: Integer Extensions
//Add space before Integer
extension Int {
func format(f: String) -> String {
return NSString(format: "%\(f)d", self) as String
}
}
//MARK: Double Extensions
//Add space before Double
extension Double {
func format(f: String) -> String {
return NSString(format: "%\(f)f", self) as String
}
}
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Source:
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