设置标题
迅速
button.setTitle(titleString, forState: controlState)
目标 C.
[button setTitle:(NSString *) forState:(UIControlState)];
将默认标题设置为 Hello World!
迅速
button.setTitle("Hello, World!", forState: .normal)
目标 C.
[button setTitle:@"Hello, World!" forControlState:UIControlStateNormal];