viewDidLayoutSubviews中应用终止的内存错误

Question

我在setBackgroundImage中有viewDidLayoutSubviews。它无限地调用viewDidLayoutSubviews。因此，应用程序终止会增加内存。我究竟做错了什么？它只发生在iPhone 5s中，相同的代码在iPad Air和iPhone 4s中运行良好。

[_hosStartDateBtn setBackgroundImage:[UIImage imageNamed:@"cal23.png"] forState:UIControlStateNormal];
//_hosStartDateBtn is a button added programatically in viewDidLayoutSubviews