Hover of internal controls in ScrollView

For example, picture, red View and blue View are added on ScrollView, drag upward, red view stays on top of screen, others continue scrolling, drag down, red view follows down

The code is as follows: (Note the setup problem for automatic layout in ScrollView)

 1 #import "ViewController.h" 2 @interface Viewcontroller () <UIScrollViewDelegate> 3 @property (weak, nonatomic) IB Outlet Uiscrollview *scrollview; 4 @property (weak, nonatomic) Iboutlet UIView *blueview; 5 @property (weak, nonatomic) Iboutlet UIView *redview; 6 @property (weak, nonatomic) Iboutlet Uiimageview *imageview; 7 @end 8 @implementation Viewcontroller 9-(void) Viewdidload {Ten [Super viewdidload];11 Self.scrollView.contentSi ze = cgsizemake (0, Cgrectgetmaxy (self.blueView.frame));}13-(void) Scrollviewdidscroll: (Uiscrollview *) SCROLLVIEW15 {cgfloat Imageh = self.imageview.frame.size.height;17 cgfloat OffsetY = Scrollview.contentoffset.y         if (OffsetY >= imageh) {19//Add Red Control to Controller view CGRect Redframe = self.redview.frame;21 REDFRAME.ORIGIN.Y = 0;22 Self.redView.frame = redframe;23 [Self.view addsubview:self.redview];24}els e {25//Add a red control to the controller ScrollView cgrect redframe = self.redview.frame;27 REDFRAME.ORIGIN.Y = 140;28 self.redView.frame = redframe;29 [Self.scrollview AddS        Ubview:self.redview];30}31//if (OffsetY < 0) {//CGFloat scale = 1-(OFFSETY/80); 34// Self.imageView.transform = Cgaffinetransformmakescale (scale, scale);//}36 PNS CGFloat scale = 1-(offs ETY/20); (scale >= 1)? scale:1;39 self.imageView.transform = Cgaffinetransformmakescale (scale, scale);}41 @end

Hover of internal controls in ScrollView