Is there a way to find the frame of a particular UITabBarItem
in a UITabBar
?
Specifically, I want to create an animation of an image "falling" into one of the tabs, similar to e.g. deleting an email in the Mail, or buying a track in the iTunes app. So I need the target coordinates for the animation.
As far as I can tell, there's no public API to get the coordinates, but would love to be wrong about that. Short of that, I'll have to guesstimate the coordinates using the index of the given tab relative to the tab bar frame.
Imre's implementation is missing a couple of imho important details.
So I changed his code a little bit and I came up with this:
+ (CGRect)frameForTabInTabBar:(UITabBar*)tabBar withIndex:(NSUInteger)index
{
NSMutableArray *tabBarItems = [NSMutableArray arrayWithCapacity:[tabBar.items count]];
for (UIView *view in tabBar.subviews) {
if ([view isKindOfClass:NSClassFromString(@"UITabBarButton")] && [view respondsToSelector:@selector(frame)]) {
// check for the selector -frame to prevent crashes in the very unlikely case that in the future
// objects thar don't implement -frame can be subViews of an UIView
[tabBarItems addObject:view];
}
}
if ([tabBarItems count] == 0) {
// no tabBarItems means either no UITabBarButtons were in the subView, or none responded to -frame
// return CGRectZero to indicate that we couldn't figure out the frame
return CGRectZero;
}
// sort by origin.x of the frame because the items are not necessarily in the correct order
[tabBarItems sortUsingComparator:^NSComparisonResult(UIView *view1, UIView *view2) {
if (view1.frame.origin.x < view2.frame.origin.x) {
return NSOrderedAscending;
}
if (view1.frame.origin.x > view2.frame.origin.x) {
return NSOrderedDescending;
}
NSAssert(NO, @"%@ and %@ share the same origin.x. This should never happen and indicates a substantial change in the framework that renders this method useless.", view1, view2);
return NSOrderedSame;
}];
CGRect frame = CGRectZero;
if (index < [tabBarItems count]) {
// viewController is in a regular tab
UIView *tabView = tabBarItems[index];
if ([tabView respondsToSelector:@selector(frame)]) {
frame = tabView.frame;
}
}
else {
// our target viewController is inside the "more" tab
UIView *tabView = [tabBarItems lastObject];
if ([tabView respondsToSelector:@selector(frame)]) {
frame = tabView.frame;
}
}
return frame;
}