Swift 将 UIImage图片 / NSData 和 String 相互转化

需求：将用户选择的本地图片进行缓存。

将图片 和 String 之间转换

let image = UIImage()
let imgData = UIImagePNGRepresentation(image)
print(imgData?.base64EncodedString())

String 转回 图片

var getImageData : UIImage{

    let data: NSData = NSData(base64Encoded: self, options:NSData.Base64DecodingOptions.ignoreUnknownCharacters)!

    return UIImage(data: data as Data)!

}

NSData 和 String 之间转换

do {
    //data to string
    let data: Data = try Data(contentsOf: url! as URL)
    let str = String(data: data, encoding: String.Encoding.utf8)
 
    //string to data
    let data:Data = str.data(using: String.Encoding.utf8))!
catch {
    print("Error: (data: contentsOf: url)")
}

Base64 之间转换

let string = "Hello world"
 
// 将字符串进行UTF8编码成NSData
let utf8EncodeData:NSData! = string.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: true)
 
// 将NSData进行base64编码
let base64EncodedString =  utf8EncodeData?.base64EncodedString()
print("encodedString: \(base64EncodedString)")
 
// 将base64字符串转换成NSData
let base64EncodedData = NSData(base64EncodedString:base64EncodedString,options:NSDataBase64DecodingOptions(rawValue: 0))
// 对NSData数据进行UTF8解码
let stringWithDecode = NSString(data: base64EncodedData!, encoding: NSUTF8StringEncoding)
print("base64String: \(stringWithDecode)")