Вот пример с реальными функциями просмотра и прерывания представления.
Swift:
extension UIView {
func loopViewHierarchy(block: (_ view: UIView, _ stop: inout Bool) -> ()) {
var stop = false
block(self, &stop)
if !stop {
self.subviews.forEach { $0.loopViewHierarchy(block: block) }
}
}
}
Пример вызова:
mainView.loopViewHierarchy { (view, stop) in
if view is UIButton {
/// use the view
stop = true
}
}
Обратный цикл:
extension UIView {
func loopViewHierarchyReversed(block: (_ view: UIView, _ stop: inout Bool) -> ()) {
for i in stride(from: self.highestViewLevel(view: self), through: 1, by: -1) {
let stop = self.loopView(view: self, level: i, block: block)
if stop {
break
}
}
}
private func loopView(view: UIView, level: Int, block: (_ view: UIView, _ stop: inout Bool) -> ()) -> Bool {
if level == 1 {
var stop = false
block(view, &stop)
return stop
} else if level > 1 {
for subview in view.subviews.reversed() {
let stop = self.loopView(view: subview, level: level - 1, block: block)
if stop {
return stop
}
}
}
return false
}
private func highestViewLevel(view: UIView) -> Int {
var highestLevelForView = 0
for subview in view.subviews.reversed() {
let highestLevelForSubview = self.highestViewLevel(view: subview)
highestLevelForView = max(highestLevelForView, highestLevelForSubview)
}
return highestLevelForView + 1
}
}
Пример вызова:
mainView.loopViewHierarchyReversed { (view, stop) in
if view is UIButton {
/// use the view
stop = true
}
}
Objective-C:
typedef void(^ViewBlock)(UIView* view, BOOL* stop);
@interface UIView (ViewExtensions)
-(void) loopViewHierarchy:(ViewBlock) block;
@end
@implementation UIView (ViewExtensions)
-(void) loopViewHierarchy:(ViewBlock) block {
BOOL stop = NO;
if (block) {
block(self, &stop);
}
if (!stop) {
for (UIView* subview in self.subviews) {
[subview loopViewHierarchy:block];
}
}
}
@end
Пример вызова:
[mainView loopViewHierarchy:^(UIView* view, BOOL* stop) {
if ([view isKindOfClass:[UIButton class]]) {
/// use the view
*stop = YES;
}
}];