Removing all subviews - a comparison of Objective-C vs ActionScript

, 07 Mar 2010 20:48:28 +0200

In Cocoa Touch a UIView object is similar to a DisplayObject in ActionScript. You can add a child to its "display list" by saying:

[myMainView addSubview:myOtherView];

To remove the view you say:

[myOtherView removeFromSuperview];

As far as I can tell there is no removeChild like we're used to in AS.

But what if you want to remove all of the children or subviews? Well, we're not as lucky as containers in Flex with that snazzy removeAllChildren() method, but we can loop through the list and tell each subview to remove itself like we do in plain-ol' ActionScript:

while(myMainView.children) { myMainView.removeChildAt(0); }

In Objective-C this would be:

while([[myMainView subviews] count]) { [[[myMainView subviews] objectAtIndex:0] removeFromSuperview]; }

And this works fine. But today I learned a pretty cool trick. Basically [myMainView subviews] is an array just like myMainView.children. And NSArray has this cool method called makeObjectsPerformSelector which basically means make every object in the array call whatever method you want them to.

So instead of looping through you can simply say the following:

[[myMainView subviews] makeObjectsPerformSelector:@selector(removeFromSuperview)];

How cool is that! Not exactly a [myMainView removeAllSubviews] but still :)

Playing with radial menus on the iPhone

Sat, 06 Mar 2010 18:06:42 +0200

After watching the Microsoft Courier videos on Engadget yesterday I started thinking about radial menus again. There are a few examples out there for ActionScript but I wanted to figure it out in Cocoa Touch.

So this morning I spent a couple hours throwing some code together. Basically this was the idea:

Listen for touches
On touch-start, start a timer to show the menu
On touch-end, kill the timer. The user will have lifted their finger so we don't want to show the menu
If we're showing the menu, start a timer to remove it once its shown
If a button is tapped or the timer is triggered remove the menu
If a button is tapped, do something

At the end I tossed in some animation to make it a little nicer visually. A quick vid of it is below and you can grab the Xcode project here. Its obviously not perfect, but shows shows the idea :)

paulofierro.com

Removing all subviews - a comparison of Objective-C vs ActionScript

Playing with radial menus on the iPhone