IOS checks whether the UIView is displayed on the screen, and ios checks the uiview screen.

IOS checks whether the UIView is displayed on the screen, and ios checks the uiview screen.

Reprinted please indicate the source: column of ALDRIDGE1

Header file:

/*************************************** * *************** MIT Licence ** Author: _ Cheng _ Ying _ ** Date: 2015.2.10 *************************************** * ************/@ interface UIView (UIScreenDisplaying) // determine whether the View is displayed on the screen-(BOOL) isDisplayedInScreen; @ end

Implementation File

/*************************************** * *************** MIT Licence ** Author: _ Cheng _ Ying _ ** Date: 2015.2.10 *************************************** * ************/@ implementation UIView (UIScreenDisplaying) // determine whether the View is displayed on the screen-(BOOL) isDisplayedInScreen {if (self = nil) {return FALSE;} CGRect screenRect = [UIScreen mainScreen]. bounds; // convert the Rect 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 no superview if (self. superview = nil) {return FALSE;} // if the size is CGrectZero if (CGSizeEqualToSize (rect. size, CGSizeZero) {return FALSE;} // obtain the Rect CGRect intersectionRect = CGRectIntersection (rect, screenRect) between the view and window; if (CGRectIsEmpty (intersectionRect) | CGRectIsNull (intersectionRect) {return FALSE;} return TRUE ;}

Test cases:

UIView * v = [[UIView alloc] initWithFrame: CGRectMake (0, 0, 40, 40)]; // No parent view BOOL b1 = [v isDisplayedInScreen]; NSLog (@ "b1: % d", b1); // [self. view addSubview: v]; BOOL b2 = [v isDisplayedInScreen]; NSLog (@ "b2: % d", b2); v. frame = CGRectZero; BOOL b3 = [v isDisplayedInScreen]; NSLog (@ "b3: % d", b3); CGRect screenRect = [UIScreen mainScreen]. bounds; CGFloat screenWidth = screenRect. size. width; CGFloat screenHeight = screenRect. size. height; v. frame = CGRectMake (-screenWidth,-screenHeight, screenWidth, screenHeight); BOOL b4 = [v isDisplayedInScreen]; NSLog (@ "b4: % d", b4 );