Several IOS rest access and interface development frameworks

Asihttprequest: http://allseeing-i.com/ASIHTTPRequest/
Asihttprequest is an open-source encapsulated class library package for accessing Web services through the cfnetwork API. Data can be submitted and returned, request and response header information can be accessed, tasks can be run in the background, download content can be downloaded to memory or saved to disk, cookies and proxies are supported;

JSON framework (aka sbjson): http://stig.github.com/json-framework/
A good JSON development kit.

Yajl: http://github.com/gabriel/yajl-objc
JSON class library package, supports stream parsing;

KIT: http://getsharekit.com/
The open-source class library of the iOS app Social Network Sharing Service supports sharing with delicious, email, Facebook, Google Reader, instaper, pinboard, read it later, Tumblr, Twitter, etc. It is quite simple to integrate with it, only three lines of code are required.

Three20: http://three20.info
A well-known open-source objective-C class library for iOS application development, which is used by many well-known brand developers including Facebook, posterous, pulse, and meetup.com. The class library adopts a modular design. You can select the corresponding modules as needed during development. Contains the encapsulation of buttons, tables, Tab controls, text labels, and special view controls. It also provides functions such as network caching, remote image access, permanent data storage, HTTP access, JSON parsing, view navigation, and CSS styles.

Core-plot: http://code.google.com/p/core-plot