bug-Assertion failure in [MyClass layoutSublayersOfLayer:]

这是在iOS7上，tableview 的sectionHeaderView中报错

*** Assertion failure in -[****.****UITVSectionHeader_Team layoutSublayersOfLayer:], /SourceCache/UIKit/UIKit-2935.137/UIView.m:8794

libc++abi.dylib: terminate_handler unexpectedly threw an exception

解决方法：在其layoutSubviews方法中只写super.layoutSubviews()即可（注明：该header
view用的是layout布局）

  override func layoutSubviews() {
        super.layoutSubviews()
    }