UIButton上字体的对齐方式

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)];