ios - 同步改变和移动 UIView

Question

如果我同时做

CGRect centView = rootview.frame;
centView.origin.x = rootview.frame.origin.x;
centView.origin.y =   your_float;
centView.size.height = screenHeight - (your_float * 2);
rootview.frame = centView;

和

CGRect frame = myview.frame;
frame.origin.x = myview.frame.origin.x;
frame.origin.y =   20 - shift - 3;
myview.frame = frame;

和

myview 在 rootview 中，然后 myview 不会移动和移动。他们如何一起工作？