iOS determines if UIView is displayed on the screen

@interface

-(BOOL) Isdisplayedinscreen;

@end

@implementation

UIView (uiscreendisplaying)

Determine if the view is displayed on the screen

-(BOOL) isdisplayedinscreen{

if (self = = nil) {

return FALSE;

}

CGRect screenrect = [UIScreen mainscreen].bounds;

Convert view to Rect for window

CGRect rect = [self convertRect:self.frame fromview:nil];

if (Cgrectisempty (rect) | | Cgrectisnull (rect)) {

return FALSE;

}

If view is hidden

if (Self.hidden) {

return false;

}

If there is no Superview

if (Self.superview = = nil) {

return false;

}

　　

If size is Cgrectzero

if (Cgsizeequaltosize (Rect.size, Cgsizezero)) {

return false;

}

Gets the rect that the view crosses with the window

CGRect intersectionrect = cgrectintersection (rect, screenrect);

if (Cgrectisempty (intersectionrect) | | Cgrectisnull (Intersectionrect)) {

return false;

}

Retrun true;

}

@end

Test case

UIView *view = [UIView alloc] Initwithframe:cgrectmake (0,0,40,40)];

No parent view

BOOL B1 = [view Isdisplayedinscreen];

NSLog (@ "B1:%d", B1);

[Self.view Addsubview:view];

BOOL B2 = [view Isdisplayedinscreen];

NSLog (@ "b2:%d", B2);

V.frame = Cgrectzero;

BOOL B3 = [view Isdisplayedsceen];

NSLog ("b3:%d", B3);

CGRect screenrect = [UIScreen mainscreen].bounds;

CGFloat screenwidth = screenRect.size.width;

CGFloat screenheight = screenRect.size.height;

View.frame = CGRectMake (-screenwidth,-screenheight, ScreenWidth, screenheight);

BOOL b4 = [view Isdisplayedinscreen];

NSLog (@ "b4:%d", B4);

iOS determines if UIView is displayed on the screen