这是一种匿名函数的写法，需要在匿名函数外面加一个小括号
UIButton*wanderButton = ({
UIButton*btn = [UIButtonbuttonWithType:UIButtonTypeCustom];
btn;
});
wonder:
- verb
- to think about something that you are not sure and try to guess what is true.
- what are they going to do now? I wonder
wonder:
- verb
- to walk slowly across an area
- I will wander around the mall for half an hour
