Go to itunes.com/apps/PlecoChineseDictionary to instantly download the free basic version of Pleco for iPhone / iPod Touch / iPad; you can add on more advanced features / dictionaries from right inside of the app, but the basic version is an excellent little dictionary in its own right (and includes the same wonderful search engine as our more advanced software).
OCR - our latest and greatest new feature; point your iPhone's camera at a printed Chinese word to instantly look up its meaning. You don't even need to take a picture, it works on the live camera video feed. Also includes experimental support for OCR from still images (a full page at a time) - we're working on fully supporting that and on adding lots of other great features in future releases. See the OCR demo video here (or here if you can't access YouTube) for a better idea of what this is all about; there's more information and a few screenshots in the instruction manual here.
Great Dictionaries - we've licensed more than a dozen of the world's best Chinese dictionaries to embed in our software, including the ABC Chinese-English Comprehensive Dictionary edited by John DeFrancis (with almost 200,000 entries), the brand-new ABC English-Chinese Dictionary also edited by John DeFrancis, the Chinese-Chinese Xiandai Hanyu Guifan Cidian, the 280,000-entry 21st Century English-Chinese Dictionary, and the Tuttle Learner's Chinese-English Dictionary. (several free dictionaries like CC-CEDICT and HanDeDict are also available as free downloads)
Fullscreen Handwriting Recognizer - our software is available with a fullscreen Chinese handwriting recognizer, letting you use the entire width of the iPhone's screen to draw characters and clear / backspace / finish entering characters using multitouch (two-finger tap). It's extremely accurate, tolerant of stroke order mistakes, and supports cursive writing, helpful for more advanced users (or for asking people to write down what they're saying when you can't understand them).
Flashcard System - create a card from any dictionary entry with a single button tap, import premade word lists, automatically optimize which cards come up the most often based on how well you remember them, and test vocabulary in a variety of ways including multiple-choice tests and tone drills.
Fantastic Performance - we've been refining our software for 10 years, and our search engine (though extremely powerful / flexible) was originally developed to offer decent performance even on a late-90s vintage Palm Pilot, so searches and dictionary entry rendering are very fast.
Powerful Search - look up words by Chinese characters, Pinyin (with or without tones), or a combination of characters and Pinyin, with support for wildcards and for full-text search to find words appearing anywhere in a dictionary definition.
Cross-referencing - tap on any Chinese character / word in any dictionary entry to look up its definition; you can also magnify / look up those words, or bring up additional information (from the Unihan character database) on individual characters.
Audio Pronunciation - instantly hear a native-speaker audio recording of each Chinese headword; recordings are available for over 34,000 words.
Stroke Order Diagrams - view beautiful, smooth animations of how to draw each character; over 20,000 characters are covered.
Document Reader - open a Chinese-language text file (uploaded from your computer or downloaded via a built-in web browser) and look up unknown words simply by tapping on them. You can also look up characters on web pages and in Word documents via the pasteboard, and can bring in text from other iPhone apps through the pasteboard as well.
Taiwan- and Mainland-friendly - supports both traditional and simplified characters (in dictionary definitions, stroke order diagrams, searches, and the handwriting recognizer), and supports Zhuyin (experimentally) as well as Pinyin for headword search and display.
Pleco for iOS should work on any model of iPhone, iPod Touch, or iPad running iOS version 6.1 or later - that means you'll need an iPhone 3GS/4/4S/5, iPod Touch 4th/5th-generation, or an iPad 2 or newer (including the iPad Air and Mini). However, in our next major update we'll be requiring iOS 7.1, so if you'd like to be able to run that you'll need at least a 5th-generation iPod or an iPhone 4/4S/5 (but any iPad 2/3/4/Air or any iPad Mini will work) In general, we would not recommend buying any iPhone older than an iPhone 4S at this point; the 4 is really starting to show its age performance-wise.
All of these devices should generally update themselves to the latest OS version automatically; connect your device to your computer and you'll be prompted to update.
Pleco is a "Universal" app and works in full-screen resolution on the iPad; we've even enhanced the user interface for iPad in a few places, it really makes our document reader function sing.
You don't need a special Chinese-version iPhone / iPod, Pleco works great regardless of where you purchased it / what language the operating system is configured to use.
An internet connection (WiFi or cellular) is required to purchase and download add-on dictionaries and other features; once those are downloaded, though, Pleco can run quite happily without any internet connection required.
See this page for instructions on migrating a previously-purchased Pleco license for Palm OS or Windows Mobile to the iPhone version of Pleco.