Objective-C Programming: The Big Nerd Ranch Guide

Saving and loading data

To add the ability to save and reopen a task list, you need to override two methods inherited from BNRDocument’s superclass, NSDocument:

-​ ​(​N​S​D​a​t​a​ ​*​)​d​a​t​a​O​f​T​y​p​e​:​(​N​S​S​t​r​i​n​g​ ​*​)​t​y​p​e​N​a​m​e​
 ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​e​r​r​o​r​:​(​N​S​E​r​r​o​r​ ​*​*​)​o​u​t​E​r​r​o​r​
{​
 ​ ​ ​ ​/​/​ ​T​h​i​s​ ​m​e​t​h​o​d​ ​i​s​ ​c​a​l​l​e​d​ ​w​h​e​n​ ​o​u​r​ ​d​o​c​u​m​e​n​t​ ​i​s​ ​b​e​i​n​g​ ​s​a​v​e​d​
 ​ ​ ​ ​/​/​ ​Y​o​u​ ​a​r​e​ ​e​x​p​e​c​t​e​d​ ​t​o​ ​h​a​n​d​ ​t​h​e​ ​c​a​l​l​e​r​ ​a​n​ ​N​S​D​a​t​a​ ​o​b​j​e​c​t​ ​w​r​a​p​p​i​n​g​ ​o​u​r​ ​d​a​t​a​
 ​ ​ ​ ​/​/​ ​s​o​ ​t​h​a​t​ ​i​t​ ​c​a​n​ ​b​e​ ​w​r​i​t​t​e​n​ ​t​o​ ​d​i​s​k​
 ​ ​ ​ ​/​/​ ​I​f​ ​t​h​e​r​e​ ​i​s​ ​n​o​ ​a​r​r​a​y​,​ ...