Extensions are basically similar to an Objective-C category. Extensions are sort of methods adding in a Classe or Structure in a different flavour.<\/p>\n
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<\/b>\u00a0extension.<\/p>\n Note:<\/b> NSData has an initializer that looks takes a bytes pointer: init(bytes: UnsafeMutablePointer , length: Int).<\/p>\n You can read more about unsafe pointer parameters in Apple’s Interacting with C APIs<\/p>\n\n\n
\n \n extension UIColor<\/span>\r\n{\r\n \/\/Fill in the blank\r\n}<\/pre>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\nCommon Extensions List:<\/h1>\n
NSData\u00a0Extensions:<\/h3>\n
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\n \n \/\/MARK: NSData Extensions\r\nextension NSData<\/span> {\r\n \r\n \/\/ Convert Data to HexString mostly used in Encrypton Algos\r\n public var hexString: String {\r\n return self.toHexString()\r\n }\r\n \r\n func toHexString() -> String {\r\n let count = self.length \/ sizeof(UInt8)\r\n var bytesArray = [UInt8](count: count, repeatedValue: 0)\r\n self.getBytes(&bytesArray, length:count * sizeof(UInt8))\r\n \r\n var s:String = \"\";\r\n for byte in bytesArray {\r\n s = s + String(format:\"%02X\", byte)\r\n }\r\n return s;\r\n } \r\n\r\n\t\/\/ Return Swift Array from NSData\r\n \r\n \r\n public func arrayOfBytes() -> [UInt8] {\r\n let count = self.length \/ sizeof(UInt8)\r\n var bytesArray = [UInt8](count: count, repeatedValue: 0)\r\n self.getBytes(&bytesArray, length:count * sizeof(UInt8))\r\n return bytesArray\r\n }\r\n \r\n \/\/ Return array from NSData\r\n class public func withBytes(bytes: [UInt8]) -> NSData {\r\n return NSData(bytes: bytes, length: bytes.count)\r\n }\r\n}<\/pre>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\nNSFileManager\u00a0Extensions:<\/h3>\n
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\n \n \/\/MARK: NSFileManager Extensions\r\n\r\nextension NSFileManager<\/span> {\r\n class func documentsDirectory() -> String {\r\n var paths = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true) as! [String]\r\n return paths[0]\r\n }\r\n \r\n class func cachesDirectory() -> String {\r\n var paths = NSSearchPathForDirectoriesInDomains(.CachesDirectory, .UserDomainMask, true) as! [String]\r\n return paths[0]\r\n }\r\n}\r\n<\/pre>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\nArray Extensions:<\/h3>\n
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\n \n \/\/MARK: Array Extensions\r\nextension Array<\/span> {\r\n \r\n \/\/Array First Object\r\n \r\n func firstObject() -> T! {\r\n var firstItem: T!\r\n if !self.isEmpty {\r\n firstItem = self[0]\r\n }\r\n return firstItem\r\n }\r\n \r\n \/\/Array Last Object\r\n \r\n func lastObject() -> T! {\r\n var lastItem: T!\r\n if !self.isEmpty {\r\n lastItem = self[self.count-1]\r\n }\r\n \r\n return lastItem\r\n }\r\n \r\n \r\n \r\n \/\/ Remove Object from Array similar to [ArrayObjec removeObject:(id)] in Objective-C\r\n\r\n mutating func removeObject(object: U) -> Bool {\r\n for (idx, objectToCompare) in enumerate(self) {\r\n if let to = objectToCompare as? U {\r\n if object == to {\r\n self.removeAtIndex(idx)\r\n return true\r\n }\r\n }\r\n }\r\n return false\r\n }\r\n \r\n \/\/ Check Array contains Object similar to [ArrayObjec containsObject:(id)] in Objective-C\r\n \r\n func contains(obj: T) -> Bool {\r\n return self.filter({$0 as? T == obj}).count > 0\r\n }\r\n}\r\n\r\n<\/pre>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\nNSObject Extensions:<\/h3>\n
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\n \n \/\/ Perform selector after delay in swift\r\n\r\nextension NSObject<\/span> {\r\n \r\n func callSelectorAsync(selector: Selector, object: AnyObject?, delay: NSTimeInterval) -> NSTimer {\r\n \r\n var timer = NSTimer.scheduledTimerWithTimeInterval(delay, target: self, selector: selector, userInfo: object, repeats: false)\r\n return timer\r\n }\r\n}\r\n<\/pre>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\nLocalization String Extensions:<\/h3>\n