I count three people in my access logs who got here by searching for iPhone programming material, two who are trying to create nibless apps. Rock on, fellow Interface Builder haterz!

iPhone programming is typically very similar to Mac programming. One big change I’ve noticed is that they’ve moved the origin for view coordinates. For NSView on the Mac, the origin point is at the lower left corner, Y coords get bigger as you move up the window. That always seemed deeply, profoundly wrong to me. I guess I’m not the only one who feels that way, because on the iPhone, the origin point is now in the upper left corner, with Y coords getting bigger as you move down the view.

To make matters worse on the Mac, it’s possible to have an NSView with “flipped” coords. In that mode, the origin point is at the top left, as god intended. Some of the stock views are like this, I think NSTableView is one of them. Those views will go crazy if you try to set them back to the “normal” Mac way, displaying their contents incorrectly. What a mess. Looks like iPhone/UIView doesn’t have the “flipped” concept, so everything’s cool again.

Well, except for other annoyances. Today’s culprit: UITextField. This is the standard one-line text input control for the user to type into, analogous to the Mac’s NSTextField. Way, WAY more complicated than it should be. Every single thing that happens to it in its lifetime, you have to write custom code for.

Creating a UITextField and adding it to a parent view is a trial-and-error affair, sprinkled with magic pixel counts like 30.0 and 4.0 and so on. It’s not just me, that’s the way they do things in Apple’s UICatalog sample app, which shows you how to create most control types. This is bad. What if the dimensions of the control change in the next iPhone software update?

When the user touches the control, the onscreen keyboard pops up. Surprise! It will almost certainly cover the UITextField the user is typing into, so they can’t see what they’re doing. The next step is that you have to write code to scroll your view up to get out of the keyboard’s way when it appears, then scroll the view back down when the keyboard disappears. Why isn’t the iPhone OS doing this for me? Madness!

Now you must add code to your view controller’s viewWillAppear: method, to catch notifications for when the keyboard appears and disappears. Then add more code to viewWillDisappear: to disable those notifications. Then write a method that gets called when the keyboard appears or disappears, to scroll your view up or down by a magic number of pixels. UICatalog hard-codes the value 150.0, which is I suppose the height of the onscreen keyboard. That wasn’t quite right for me, I discovered I needed it to be 166.0. I’m sure that will be the right value to use always and forevermore, right Apple? Sheesh.

Finally, the keyboard won’t ever go away unless you write more code to dismiss it. You must make your view controller the text control’s delegate and write a textFieldShouldReturn: method so you can do something with the Enter key and tell the keyboard to go away. Six new methods later, your quest is at an end. Until the next time you need a UITextField.

Categories: cocoa, iphone, mac, objective-c, programming
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