为什么滚动视图即使没有 contentView 滚动到仍然滚动

Question

谁能解释为什么橙色方块不在 0 点，而我仍然可以将滚动视图上下滚动 20 像素？

导入 UIKit

类 MessageVC: UIViewController, UIScrollViewDelegate {

let scrollView = UIScrollView()


let messageHolder = MessageHolderVC()
let messageSender = MessageSenderVC()

override func viewDidLoad() {
    super.viewDidLoad()
    self.view.backgroundColor = UIColor.whiteColor()


    scrollView.frame = CGRectMake(0, 1, self.view.frame.width, self.view.frame.height - 2)
    scrollView.backgroundColor = UIColor.redColor()
    scrollView.pagingEnabled = true

    scrollView.contentSize = CGSizeMake(scrollView.frame.size.width * 2, scrollView.frame.size.height)
    scrollView.bounces = false

    self.view.addSubview(scrollView)


    messageHolder.view.frame = CGRectMake(0, 0, 20, 20)
    scrollView.addSubview(messageHolder.view)




}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}


/*
// MARK: - Navigation

// In a storyboard-based application, you will often want to do a little preparation before navigation
override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
    // Get the new view controller using segue.destinationViewController.
    // Pass the selected object to the new view controller.
}
*/

Answer 1

试试这个：在你的故事板中选择ViewController并取消选中Adjust Scroll View insets，像这样：