Ray's playground

摘要： Sharding refers to the process of splitting data up and storing different portions of thedata on different machines; the term partitioning is also sometimes used to describethis concept. By splitting ... 阅读全文

摘要： The id data type is used to store an object of any type. In a sense, it is a generic objecttype. For example, this line declares number to be a variable of type id:　　id number;　　Methods can be declare... 阅读全文

摘要： The leading minus sign (-) tells the Objective-C compiler that the method is an instancemethod.The only other option is a plus sign (+), which indicates a class method. 阅读全文