Map vs for in vs forEach Challenge

map() or for in or forEach()? Comparing performance of map method vs for in vs forEach method.

Usage

Run the command below and compare the results.

$ swift test

Modify arrayLength property in MapVsForInVsForEachChallengeTests class to check performance for longer / shorter array.

Test Environment

• Device: MacBook Pro (15-inch, Mid 2015, 2.2GHz Intel Core i7, 16GB RAM)
• OS: macOS High Sierra 10.13.4
• Swift: 4.1
• Array length: 10,000,000

Test Results

Variant	Average duration
map()	1.227 sec
for in	1.892 sec
forEach()	2.135 sec

Conclusions

map() is the fastest, forEach() is the slowest.