Objective-C Programming: The Big Nerd Ranch Guide

Nesting message sends

Message sends can be nested. For instance, to find out the number of seconds since the start of 1970, you could write your code this way:

 ​ ​ ​ ​N​S​D​a​t​e​ ​*​n​o​w​ ​=​ ​[​N​S​D​a​t​e​ ​d​a​t​e​]​;​
 ​ ​ ​ ​d​o​u​b​l​e​ ​s​e​c​o​n​d​s​ ​=​ ​[​n​o​w​ ​t​i​m​e​I​n​t​e​r​v​a​l​S​i​n​c​e​1​9​7​0​]​;​
 ​ ​ ​ ​N​S​L​o​g​(​@​"​I​t​ ​h​a​s​ ​b​e​e​n​ ​%​f​ ​s​e​c​o​n​d​s​ ​s​i​n​c​e​ ​t​h​e​ ​s​t​a​r​t​ ​o​f​ ​1​9​7​0​"​,​ ​s​e​c​o​n​d​s​)​;​

Or you could nest the two message sends like this:

 ​ ​ ​ ​d​o​u​b​l​e​ ​s​e​c​o​n​d​s​ ​=​ ​[​[​N​S​D​a​t​e​ ​d​a​t​e​]​ ​t​i​m​e​I​n​t​e​r​v​a​l​S​i​n​c​e​1​9​7​0​]​;​ ​ ​ ​ ​N​S​L​o​g​(​@​"​I​t​ ​h​a​s​ ​b​e​e​n​ ​%​f​ ​s​e​c​o​n​d​s​ ​s​i​n​c​e​ ​t​h​e​ ​s​t​a​r​t​ ​o​f​ ...