Tumblr OAuth image post gives me 401/“Invalid OAuth credentials”
问题 I've got an iOS app thats posts images to several services, including twitter and I'm trying to extend that support to tumblr. I've adapted some open source code for the OAuth 1.0a header logic and its working well enough to be successful for twitter + twitpic and for tumblr's authentication. However image posts to tumblr are failing with status 401 and string response "Invalid OAuth credentials" To simplify, my only multipart sections are the post type and the image data. So my simple POST