怎么避免我遇到的错误？

开发pieChart的时候用core plot对于给定代码添加动画：

   CABasicAnimation *rotation = [CABasicAnimation animationWithKeyPath:@"transform"];
   CATransform3D transform = CATransform3DMakeRotation(DegreesToRadians(360), 0, 0, 1);
   rotation.toValue = [NSValue valueWithCATransform3D:transform];  
    rotation.duration = 10.0f;
    [pieChart addAnimation:rotation forKey:@"rotation"];    

然后就提示出错：

Implicit declaration of function 'DegreesToRadians' is invalid in C99

运行时间也提示出错：

Apple_o  Linker id error  "_DegreesToRadians", referenced from:

这个问题实在不知道怎么解决

第一种方式：Dependent Project Install

参考链接：

 http://www.cnblogs.com/lovecode/archive/2012/02/11/2346389.html