Developing iPhone Web Apps Tutorials
Exploring Bindings / Using a Value Transformer
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Subtitles of the Movie (Developing iPhone Web Apps / Exploring Bindings / Using a Value Transformer)
Now, before moving on I want to run simulator once again. I've reconnected the binding for the description so all of the data is now showing up. We'll come down here, takes a moment to get the poster. Here is the description and here's the release date down here. Now, this takes a while. I have to scroll up and down. I wonder if there's something else that I can do to modify this and we'll stop the simulator and I want to show you one other feature that you have in the Bindings Inspector. Stop that and let's look at the description. In the Bindings Inspector you can see that it's bound to the list dataSource and it's the description field and there's this thing called a value transformer and I'll just show you one of them and then we can get into this later when we're talking about programming. I can select from various transformers and one of the ones that I'm going to look at is Dashcode transformer truncated and it will truncate that text to ten characters. Let's take a look and see what happens when I run it in the simulator. I've got the poster. I've got this text truncated to be only ten characters long so that I don't need quite so much space. Now, if I want to actually do something a little more meaningful, perhaps in this case I want to modify it so I'm truncating it to 50 characters. Let's take a look at that and see how it works. I'm still going to miss some of the text but it's not going to be quite so long as if nothing had been truncated. So here I've got the ability in the Bindings Inspector to put a value transformer on and it takes the data. Normally the binding means I take the data out of this feed and put it in this field that is selected but on the way from the feed into the field I have the ability to transform it and I have a number of built-in transformers built that are distributed with Dashcode but I can create new ones based on these models and we'll take a look at this as we start dealing with programming later on. But I just wanted you to be aware that this is the place where you manipulate the binding of the data into the field. You take it out of the feed, put it into the field and on the way create a transformation that modifies it, truncates it or makes some other change to it. You've seen this already before in the built-in browser that has the data for National Parks on it. It has a list of the National Parks on the front and if you click on one of the National Park names, it flips to the back and it says such and such a national park is very attractive this time of year. That's a transformation. It took the value of the name of a national park and added some text to it. It's the same basic principle as truncation and we'll come back to transformers because they can be very useful to you. But now we've looked at data sources, we've looked at bindings from the dataSource and from the field level and now it's time to move on and take a look at something that isn't a browser. We've spent all this time dealing with the browser template and the RSS template, which is like the browser template. Now let's move on and see what else you have built into Dashcode and how you can build on it.
Tutorial Information
| Course: | Developing iPhone Web Apps |
| Author: | Jesse Feiler |
| SKU: | 34075 |
| ISBN: | 1-935320-89-0 |
| Release Date: | 2009-12-31 |
| Duration: | 8 hrs / 103 lessons |
| Work Files: |
Yes |
| Captions: | No |
| Compatibility: |
Vista/XP/2000, OS X, Linux QuickTime 7, Flash 8 |
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