swift url or post data escape / swift post数据转义

escape.swift

func escape(str: String) -> String {
		let characterSet = NSMutableCharacterSet.alphanumericCharacterSet()
		characterSet.addCharactersInString("-._ ")
		if #available(iOS 8.3, *) { 
			return str.stringByAddingPercentEncodingWithAllowedCharacters(characterSet)!.stringByReplacingOccurrencesOfString(" ", withString: "+")
		}
		let length = str.characters.count
		let num = 50
		let times = length > (length / num * num) ? length / num + 1 : length / num
		var result = ""
		for i in 0 ..< times {
			let end = i == times - 1 ? length : num * (i+1)
			let range = (str.startIndex.advancedBy(i*num)..<str.startIndex.advancedBy(end))
			result += str.substringWithRange(range).stringByAddingPercentEncodingWithAllowedCharacters(characterSet)!.stringByReplacingOccurrencesOfString(" ", withString: "+")
		}
		return result
}