Swift Special Keywords

#available () function to check the availability of API functions

//determine if the current version is ios8.0+,osx10.10+ and on a different platformif#available (IOS8.0Os x10.10, *) {     //When the version matches} Else {      //When the version does not match} can also be placed in front of a method to make its method available in a version//ios8.0+,osx10.10+ and available on other platforms@available (IOS8.0Os x10.10, *) func startuseractivity ()-nsuseractivity {}

new guard Syntax: This new syntax allows you to build an early exit point in a code cycle, avoiding a lot of if judgments

If a >=elsereturn }

Swift Special Keywords