iOS Programming: The Big Nerd Ranch Guide, Second Edition

Blocks

Blocks as variables

Now that you have some experience with Objective-C and the iOS SDK, how would you add the colorize-on-shake and invert-color-on-rotate features? You would probably write a method that would loop over every line, perform some calculations with that line’s data, and then set its color.

/​/​ ​A​ ​c​a​n​d​i​d​a​t​e​ ​f​o​r​ ​c​o​l​o​r​i​z​e​O​n​S​h​a​k​e​ ​a​s​ ​i​m​p​l​e​m​e​n​t​e​d​ ​b​y​ ​T​o​u​c​h​D​r​a​w​V​i​e​w​ -​ ​(​v​o​i​d​)​c​o​l​o​r​i​z​e​O​n​S​h​a​k​e​ {​ ​ ​ ​ ​f​o​r​(​L​i​n​e​ ​*​l​ ​i​n​ ​c​o​m​p​l​e​t​e​L​i​n​e​s​)​ ​{​ ​ ​ ​ ​ ​ ​ ​ ​U​I​C​o​l​o​r​ ​*​c​l​r​ ​=​ ​[​s​e​l​f​ ​c​o​m​p​u​t​e​C​o​l​o​r​F​o​r​L​i​n​e​:​l​]​;​ ​ ​ ​ ​ ​ ​ ​ ​[​l​ ​s​e​t​C​o​l​o​r​:​c​l​r​]​;​ ​ ​ ​ ​}​ ​ ​ ​ ​[​s​e​l​f​ ​s​e​t​N​e​e​d​s​D​i​s​p​l​a​y​]​;​ ...