导航栏自定义一个UIBarButtonItem最快的方式

+ (UIBarButtonItem *)itemWithIcon:(NSString *)icon highIcon:(NSString *)highIcon target:(id)target action:(SEL)action
{
    UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
    [button setBackgroundImage:[UIImage imageWithName:icon] forState:UIControlStateNormal];
    [button setBackgroundImage:[UIImage imageWithName:highIcon] forState:UIControlStateHighlighted];
    button.frame = (CGRect){CGPointZero, button.currentBackgroundImage.size};
    [button addTarget:target action:action forControlEvents:UIControlEventTouchUpInside];
    return [[UIBarButtonItem alloc] initWithCustomView:button];
}