When using storyboard to automatically layout scrollview, I often report an error: Scroll View has ambiguous scrollable content height / width. The reason is that the content size of the scrollview is determined by all the subviews of the scrollview. When the scrollview cannot calculate the content size according to the subview, this error will be reported. To eliminate this error, make the scrollview's child views "touch" to the four sides of the scrollview. The final height calculated up and down and the contentView with the width of the scrollView
From: http://blog.csdn.net/man_oc/article/details/43796127