1Use in Swift {#flatbuffers_guide_use_swift} 2========= 3 4## Before you get started 5 6Before diving into the FlatBuffers usage in Swift, it should be noted that 7the [Tutorial](@ref flatbuffers_guide_tutorial) page has a complete guide 8to general FlatBuffers usage in all of the supported languages (including Swift). 9This page is designed to cover the nuances of FlatBuffers usage, specific to 10Swift. 11 12You should also have read the [Building](@ref flatbuffers_guide_building) 13documentation to build `flatc` and should be familiar with 14[Using the schema compiler](@ref flatbuffers_guide_using_schema_compiler) and 15[Writing a schema](@ref flatbuffers_guide_writing_schema). 16 17## FlatBuffers Swift library code location 18 19The code for the FlatBuffers Swift library can be found at 20`flatbuffers/swift`. You can browse the library code on the [FlatBuffers 21GitHub page](https://github.com/google/flatbuffers/tree/master/swift). 22 23## Testing the FlatBuffers Swift library 24 25The code to test the Swift library can be found at `flatbuffers/Flatbuffers.Test.Swift`. 26The test code itself is located in [Flatbuffers.Test.Swift](https://github.com/google/flatbuffers/blob/master/tests/FlatBuffers.Test.Swift). 27 28To run the tests, use the [SwiftTest.sh](https://github.com/google/flatbuffers/blob/master/tests/FlatBuffers.Test.Swift/SwiftTest.sh) shell script. 29 30*Note: The shell script requires [Swift](https://swift.org) to 31be installed.* 32 33## Using the FlatBuffers Swift library 34 35*Note: See [Tutorial](@ref flatbuffers_guide_tutorial) for a more in-depth 36example of how to use FlatBuffers in Swift.* 37 38FlatBuffers supports reading and writing binary FlatBuffers in Swift. 39 40To use FlatBuffers in your own code, first generate Swift structs from your 41schema with the `--swift` option to `flatc`. Then include FlatBuffers using `SPM` in 42by adding the path to `FlatBuffers/swift` into it. The generated code should also be 43added to xcode or the path of the package you will be using. Note: sometimes xcode cant 44and wont see the generated files, so it's better that you copy them to xcode. 45 46For example, here is how you would read a FlatBuffer binary file in Swift: First, 47include the library and copy thegenerated code. Then read a FlatBuffer binary file or 48a data object from the server, which you can pass into the `GetRootAsMonster` function. 49 50~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.swift} 51 import FlatBuffers 52 53 typealias Monster1 = MyGame.Sample.Monster 54 typealias Vec3 = MyGame.Sample.Vec3 55 56 let path = FileManager.default.currentDirectoryPath 57 let url = URL(fileURLWithPath: path, isDirectory: true).appendingPathComponent("monsterdata_test").appendingPathExtension("mon") 58 guard let data = try? Data(contentsOf: url) else { return } 59 60 let monster = Monster.getRootAsMonster(bb: ByteBuffer(data: data)) 61~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 62 63Now you can access values like this: 64 65~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.swift} 66 let hp = monster.hp 67 let pos = monster.pos 68~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 69 70 71In some cases it's necessary to modify values in an existing FlatBuffer in place (without creating a copy). For this reason, scalar fields of a Flatbuffer table or struct can be mutated. 72 73~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~{.swift} 74 let monster = Monster.getRootAsMonster(bb: ByteBuffer(data: data)) 75 76 if !monster.mutate(hp: 10) { 77 fatalError("couldn't mutate") 78 } 79 // mutate a struct field 80 let vec = monster.pos.mutate(z: 4) 81 82 // This mutation will fail because the mana field is not available in 83 // the buffer. It should be set when creating the buffer. 84 if !monster.mutate(mana: 20) { 85 fatalError("couldn't mutate") 86 } 87~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 88 89The term `mutate` is used instead of `set` to indicate that this is a special use case. All mutate functions return a boolean value which is false if the field we're trying to mutate is not available in the buffer. 90 91<br> 92