March 2013
Intermediate to advanced
1000 pages
34h 51m
English
Content preview from Programming iOS 6, 3rd EditionBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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UIPickerView
A UIPickerView displays selectable choices using a rotating drum metaphor. It has a standard legal range of possible heights, which is undocumented and must be discovered by trial and error (attempting to set the height outside this range will fail with a warning in the console); its width is largely up to you. Each drum, or column, is called a component.
Your code configures the UIPickerView’s content through its data source (UIPickerViewDataSource) and delegate (UIPickerViewDelegate), which are usually the same object (see also Chapter 11). Your data source and delegate must answer questions similar to those posed by a UITableView (Chapter 21):
-
numberOfComponentsInPickerView:(data source) - How many components (drums) does this picker view have?
-
pickerView:numberOfRowsInComponent:(data source) -
How many rows does this component have? The first component is numbered
0. -
pickerView:titleForRow:forComponent:pickerView:attributedTitleForRow:forComponent:(new in iOS 6)pickerView:viewForRow:forComponent:reusingView:(delegate) -
What should this row of this component display? The first row is numbered
0. You can supply a simple string, an attributed string (Chapter 23), or an entire view such as a UILabel; but you should supply every row of every component the same way. ThereusingViewparameter, if not nil, is a view that you supplied for a row now no longer visible, giving you a chance to reuse it, much as cells are reused in a table view.
Here’s the code for a UIPickerView ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.