In this chapter, we have implemented a business application that accesses the Internet to get its list of exchange rates and displays the exchanged values in a table.
Specifically, we covered the basics of XML and how to use NSURL and NSXMLDocument to download an XML file from the Internet. We continued by covering how to access, using paths, the XML Elements that we want in the XML document and how to use a background NSThread so that our main user interface thread is not tied up by another task. Then we looked at how to populate and act on NSPopUpButton objects and how to populate NSTableView objects. Finally, we covered how to access the AppDelegate from another object to retrieve values and then perform arithmetic operations on them.
Now that we've learned how to access XML files from the Internet, we are going to look at the Internet using its new marketing name of, the Cloud. We will look at how so-called "Cloud services", specifically iCloud, can be used to not only retrieve...