const修饰位置不同，代表什么？

1.const NSString *HSCoder = @"汉斯哈哈哈";
2.NSString const *HSCoder = @"汉斯哈哈哈";
3.NSString * const HSCoder = @"汉斯哈哈哈";

1.const NSString *HSCoder = @"汉斯哈哈哈"; 
"*HSCoder"不能被修改， "HSCoder"能被修改 
2.NSString const *HSCoder = @"汉斯哈哈哈"; 
"*HSCoder"不能被修改， "HSCoder"能被修改
3.NSString * const HSCoder = @"汉斯哈哈哈"; 
"HSCoder"不能被修改，"*HSCoder"能被修改 注意：1和2其实没什么区别

参考:http://www.jianshu.com/p/f83335e036b5