在swift-3中访问NS Type类类别

Question

I've NSData category for base64Encoding written in Obj-C.

@interface NSData (Base64)

+ (NSData*)dataFromBase64String:(NSString*)aString;
- (NSString*)base64EncodedString;

@end

Initially in Swift 2.2, I was using it as:

let dbPassData = NSData(fromBase64String: password)

Now, in Swift 3, there is no any NSData , instead have Data .

How to use these category methods in swift 3?

---

After converting project to Swift 3, it converted that line as:

let dbPassData = Data(fromBase64String: password)

which yields an error:

Argument labels do not match any available overloads

Answer 1

In Swift 3, Apple also renamed some initializers and Xcode 8 beta makes some mistakes when converting from 2.2 to 3.

In that case, the initializer was renamed to this:

let data = Data(base64Encoded: "hello")

---

When you are facing this or similar problems, you can start typing ClassName( and look at the proposed initializers. In most cases, you'll find the new one easily.

Answer 2

NSData is still available in Swift 3, just like String has been coexisting with NSString . You need to ignore the compiler's advice in this case:

let dbPassData = NSData(fromBase64String: password) as Data

This assumes you don't want to port your Base64 category to Swift or you want to maintain compatibility with Obj-C code. Swift 3's Data also offer built-in Base 64 conversion:

let dbPassData   = Data(base64Encoded: password)
let base64String = data.base64EncodedString(options: [.lineLength64Characters, .endLineWithLineFeed])