为什么我们仍然在swift ios应用程序中使用NSDictionary和NSArrays？

Question

I see a lot of code for swift ios tutorials on the internet still using the old objective-c data types like NSDictionary and NSArrays instead of using the modern Array and Dictionary data types that come with Swift.

Most often I see a lot of type casting going on using as? etc. I have seen this mostly in examples involving json parsing from a webservice.

So why is this? Is this because swift isn't fully compatible withe cocoa touch apis yet? Or is there another reason like performance?

Answer 1

Even though you used the NSArray and NSDictionary, swift will automatically bridges to their native swift equivalent Array and Dictionary.

By using the Swift native, the performance will be great.

Please refer the documentation

Answer 2

Because you are calling code in the Cocoa library that uses NSDictionary and NSArray and Apple isn't going to rewrite all these libraries.

Your question whether Swift is not fully compatible with Cocoa APIs is nonsensical. It is compatible, or you couldn't call Cocoa. But the Cocoa APIs are not changing. Cocoa is a library; it uses and supports the classes that it uses and supports, and using a different programming language isn't going to change that.