构造函数想要一个数组文字而不是数组，所以你可以用这样的东西初始化

let healthWrite = Set(arrayLiteral:
     HKObjectType.quantityTypeForIdentifier(HKQuantityTypeIdentifierBodyMassIndex)!,
     HKObjectType.quantityTypeForIdentifier(HKQuantityTypeIdentifierActiveEnergyBurned)!,
     HKObjectType.quantityTypeForIdentifier(HKQuantityTypeIdentifierDistanceWalkingRunning)!,
     HKQuantityType.workoutType()
     )

更多关于数组和数组文字https://developer.apple.com/library/prerelease/ios/documentation/Swift/Conceptual/Swift_Programming_Language/CollectionTypes.html

编辑：

给你带来痛苦的是可选值，而不是“[]”

let healthWrite = Set([
            HKObjectType.quantityTypeForIdentifier(HKQuantityTypeIdentifierBodyMassIndex)!,
            HKObjectType.quantityTypeForIdentifier(HKQuantityTypeIdentifierActiveEnergyBurned)!,
            HKObjectType.quantityTypeForIdentifier(HKQuantityTypeIdentifierDistanceWalkingRunning)!,
            HKQuantityType.workoutType()]
            )

如果您使用guard或if让检查HKObjectType，则效果更好。quantityTypeForIdentifier实际上在创建集合之前返回一个值