参考:http://www.cnblogs.com/sunshine-anycall/p/4185304.html
两行代码搞定:
[[UIBarButtonItemappearanceWhenContainedInInstancesOfClasses:@[[UISearchBarclass]]]setTitle:@"取消"];
[[UIBarButtonItemappearanceWhenContainedInInstancesOfClasses:@[[UISearchBarclass]]]setTintColor:[UIColorwhiteColor]];
