设置UIButton上字体的对齐方式，不是用：
[Button.titleLabel setTextAlignment:UITextAlignmentCenter];
而是用：
[Button setContentHorizontalAlignment:UIControlContentHorizontalAlignmentCenter];
typedefNS_ENUM(NSInteger, UIControlContentHorizontalAlignment)
{
UIControlContentHorizontalAlignmentCenter = 0,
UIControlContentHorizontalAlignmentLeft = 1,
UIControlContentHorizontalAlignmentRight = 2,
UIControlContentHorizontalAlignmentFill = 3,
};
改动button上文字位置的方法
[UIButton setTitleEdgeInsets:UIEdgeInsetsMake(9-3, 8, 9+3, 2)];
改动button上图片位置的方法
[UIButton setImageEdgeInsets:UIEdgeInsetsMake(9-3, 2, 9+3, 2)];