Objective C

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You use the Newsstand Kit framework to develop the client side of a Newsstand application. Through the Newsstand, users can browse through newspapers and magazines that are optimized for viewing on mobile devices. The Newsstand Kit framework has three classes: NKLibrary—Represents the application’s library of newsstand issues.NKIssue—Represents a publication’s issue in the library.NKAssetDownload—Represents an asset that is downloaded (or that has downloaded) from the application’s server. An asset can be a component of the online issue such as an HTML or image file. It can also be a compressed archive (such as a ZIP file) that, once uncompressed, contains all the components of an issue in a ready-to-display form. Newsstand Kit Framework Reference Newsstand Kit Framework Reference
Calculate Downloadtime Calculate Downloadtime The naïve way is bytes_downloaded / (now - start_time), but that becomes inaccurate if the connection speed fluctuates wildly, or if the user starts another download (perhaps in another app) halfway through your download. Both of these may happen if the user runs a torrent in the background. A better way (though harder to implement) is to keep an array of periodic samples and present the average.
Automatic Reference Counting Automatic Reference Counting Friday Q&A 2011-09-30: Automatic Reference Counting Since the moment Apple announced it, readers have asked me to write about Automatic Reference Counting, or ARC. Today is the day. I'll talk about Apple's new memory management system, how it works, and how to get the most out of it. ConceptualThe Clang static analyzer is a really useful tool for finding memory management errors in code.