objective-c - ios 按钮控件点击后，左上角有蓝色小块

Question

如图，那个蓝色小块是怎么回事？？不是每次都显示的

Answer 1

Change buttonType to UIButtonTypeCustom and try it

Answer 2

I don’t know what this is. I feel like there is a view with a small label on it. If the characters on the view with a small label are empty, your view will be displayed like this.
It is recommended that you use reveal to take a look.