How to Debug and see NSData / Data in Xcode debugger

Xcode’s debugger is bad about letting you see what the contents of a Data / NSData object are. Here’s my workaround:

  1. Use po to print out the base64 version of the object, e.g.
po defaultDownloadResponse.data?.base64EncodedString()

2. Copy that to the clipboard, then use the command line in Terminal to turn that into readable content

pbpaste | base64 -D | xxd

If you know it is plain text you can omit the xxd part.

For example, here’s the output for a recent AlamoFire debugging session:

(lldb) po defaultDownloadResponse.data?.base64EncodedString()
Optional<String>
some : "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"
? pbpaste | base64 -D | xxd
00000000: 7b22 7375 6363 6573 7322 3a74 7275 652c  {"success":true,
00000010: 2270 726f 6669 6c65 223a 7b22 7072 6f66  "profile":{"prof
00000020: 696c 6573 223a 5b7b 2266 696c 7465 7261  iles":[{"filtera
00000030: 626c 6522 3a66 616c 7365 2c22 6669 6c74  ble":false,"filt
00000040: 6572 5f70 7269 6f72 6974 7922 3a6e 756c  er_priority":nul
00000050: 6c2c 2266 696c 7465 725f 7465 7874 223a  l,"filter_text":
00000060: 6e75 6c6c 2c22 6669 6c74 6572 5f70 6172  null,"filter_par
00000070: 616d 6574 6572 7322 3a7b 7d2c 2271 7565  ameters":{},"que
00000080: 7374 696f 6e5f 6963 6f6e 223a 2242 6173  stion_icon":"Bas
00000090: 6963 735f 3030 3222 2c22 7175 6573 7469  ics_002","questi
000000a0: 6f6e 5f69 6422 3a32 2c22 7461 6773 223a  on_id":2,"tags":
000000b0: 5b22 6f70 696e 696f 6e73 225d 2c22 6465  ["opinions"],"de
000000c0: 636c 696e 6564 5f71 7565 7374 696f 6e22  clined_question"
000000d0: 3a66 616c 7365 2c22 636f 6d6d 656e 7422  :false,"comment"
000000e0: 3a22 222c 2263 7265 6174 6564 5f61 7422  :"","created_at"
000000f0: 3a22 3230 3230 2d31 322d 3038 5431 373a  :"2020-12-08T17:
00000100: 3335 3a31 322e 3937 355a 222c 2275 7064  35:12.975Z","upd
00000110: 6174 6564 5f61 7422 3a22 3230 3230 2d31  ated_at":"2020-1
00000120: 322d 3038 5431 373a 3335 3a31 322e 3937  2-08T17:35:12.97
00000130: 355a 222c 2263 686f 6963 6573 223a 5b7b  5Z","choices":[{
00000140: 226f 7264 6572 223a 302c 2261 6374 6976  "order":0,"activ
00000150: 6522 3a74 7275 652c 2269 6422 3a31 3131  e":true,"id":111
00000160: 3938 2c22 6368 6f69 6365 5f69 6422 3a32  98,"choice_id":2
00000170: 392c 2263 7573 746f 6d5f 656e 7472 6965  9,"custom_entrie
00000180: 7322 3a5b 5d2c 2263 7265 6174 6564 5f61  s":[],"created_a
00000190: 7422 3a22 3230 3230 2d31 322d 3130 5431  t":"2020-12-10T1
000001a0: 353a 3439 3a32 392e 3430 385a 227d 5d7d  5:49:29.408Z"}]}
000001b0: 5d7d 7d                                  ]}}

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