A pair of iPhone app from Omar Rabbolini, an Italian application developer currently resides in UK. These pair of iPhone apps: CantoNotes and Hanzi Lookup, will help Cantonese speaking users not familiar with writing Chinese; like myself, learn to write Chinese characters.
CantoNotes will allow users to enter Chinese characters using the LSHK (Linguistic Society of Hong Kong) JyutPing standard phonemes input method and CantoNotes will respond with the corresponding Chinese character. Characters displayed can be copy and paste into the built in Hanzi Lookup screen. Rather than using the built in copy & paste feature of iPhone OS, the app use its own Copy and Paste buttons. Although the iPhone OS built in copy & paste feature also works. After pasting the desired Chinese characters into the Hanzi Lookup screen, it will display the Chinese character in a medium size font, along with the Cantonese pronunciation beneath it one character at a time.
Not sure what the built in Hanzi Lookup screen is for, as the shown information is already shown in the main screen of CantoNotes. The program does have a reference in the Hanzi Lookup screen to the iTunes App Store page for the separate Hanzi Lookup app.
The Hanzi Lookup app allows users to locate meanings of Chinese characters in English, plus it provides pronunciations for the Chinese character in both Mandarin and Cantonese, along with the phonemes to enter the Chinese character in JyutPing and PingYin.
The developer is asking a relatively steep USD1.99 and USD0.99 for CantoNotes [iTunes App Store link] and Hanzi Lookup [iTunes App Store link] respectively. Given the functionalities of these application, I suggest you give it a pass.