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iOS Build a Simple iPhone App with Objective-C Debugging Our App Breakpoints

Pablo Alfaro
PLUS
Pablo Alfaro
Courses Plus Student 6,923 Points
Posted by Pablo Alfaro
Pablo Alfaro
Courses Plus Student 6,923 Points

Confused about random number generated

I am little confused about the random number generated. The random number produces a large negative number and then it is converted into a smaller number within the bounds of the facts array. How is this number converted from large negative to a small positive number?

Here is the large negative number after pressing the 'show another fun fact' button my screenshot/ image link

Here is the generated number after stepping into the next steps my screenshot/ image link

1 Answer

Andrew Davis
Andrew Davis
6,367 Points

I believe arc4random_uniform() returns essentially a 32-bit pseudo-random number between -2,147,483,648 (-1 × 231) through 2,147,483,647 (231 - 1), then adjusts it to positive. But with the limit you've put on it (the self.facts.count), it is partitioning that number range by your limit, and giving you the order of the partition (in this case the 2nd).