zxing barcode generator example c# 11: iBooks and E-Books in Objective-C

Draw qr-codes in Objective-C 11: iBooks and E-Books

Note Real literals without a suffix are of type double, not float!

This method of reading and writing to and from servers is acceptable for some situations, but it is fundamentally flawed for responsive gaming. The main problem with NSString s stringWithContentsOfURL: is that it loads the content of the URL synchronously, meaning that it blocks the current program loop until it finishes loading. This is clearly not ideal, because your application will stop responding for the duration of URL request, which itself can take some time to complete. In order to run nonblocking, or asynchronous, URL requests, you can use NSURLConnection class methods. When using NSURLConnection to make URL requests, the actual request is handled in the background, allowing the rest of the program to continue running. When data is obtained, or even when the request fails, a chosen delegate object is notified to handle the data. Listing 8-2 shows a method that initiates the retrieval of information from a web page (here a simple PHP page, score.php) using NSURLConnection. Listing 8-3 shows the associated delegate methods.

Once everything was documented for Snow Reports, I needed to make sure that I had a signed data usage agreement from OnTheSnow.com. I can only imagine the state of insanity that would occur if I were halfway through development only to find that the folks at OnTheSnow.com had changed their minds before signing. Likewise, I recommend that you identify and acquire your third-party resources up front. Do you need data for your application You will need to find a data provider, contact that company, and negotiate to gain access to its data. Do you need to purchase or have sound effects created Do you need to purchase any stock icons or graphics List all of these requirements, especially if they have costs attached to them. Three sound effects might be cheap, but if you need fifty of them for a game, the costs can quickly add up. It s no use worrying over the development of an application if you can t get the data or the media it needs to function.

The WSDL 1.1 specification that describes the complete document structure can be found at http://www.w3.org/TR/wsdl. It is worth looking at the original specification because you will find useful elements that you can use even though they are not widely known or even generated using GUI tools such as Visual Studio .NET. For example, the <operation> element contains a child element called <documentation> that allows you to insert an English language description of what the operation does. Here is an example: <operation name="RequestQuote"> <documentation> Returns a delayed 30-minute quote for a given stock ticker symbol. This operation returns a Quote XML type as defined in the XSD schema at: http://www.bluestonepartners.com/schemas/StockTrader.xsd </documentation> <input message="s1:RequestQuoteSoapIn" /> <output message="s1:RequestQuoteSoapOut" /> </operation> The <documentation> element adds a welcome level of readability to the WSDL document, which is challenging at best to read with human eyes. If you were to distill a WSDL document down to its most basic set of associated elements, it would look like this: <definitions> <types /> <message /> <operation> <message /> </operation> <portType> <operation /> </portType>

You ve already seen how a business rule is defined based on the RuleHandler delegate. A key part of what ValidationRules does is keep a list of such rule methods for each of the business object s properties. To do this, it relies on two other classes: ValidationRulesManager and SharedValidationRulesManager. The ValidationRulesManager class keeps a list of rules for each property. One way ValidationRulesManager is used is to keep a list of rules that is unique for each instance of a business object. This means that each time a business object is created, a set of rules can be associated with the properties of that particular instance. This has a pretty big impact on performance and memory consumption, and it s usually not the right approach. However, sometimes objects really do need unique rules, and this class enables that scenario. Another way ValidationRulesManager is used is by the SharedValidationRulesManager class, because it keeps a list of rules for each business type. The SharedValidationRulesManager class keeps a list of rules for each property that is common across all instances of a business object type. This means that the first time an instance of a given business class is created, the rules are associated with the properties of that type. The resulting associations are cached for the lifetime of the application and are shared by all instances of that business class. This has good performance and minimal memory consumption, and it s the recommended approach.