1Protocol Buffers - Google's data interchange format 2=================================================== 3 4[](https://fusion.corp.google.com/projectanalysis/current/KOKORO/prod:protobuf%2Fgithub%2Fmaster%2Fmacos%2Fobjectivec_cocoapods_integration%2Fcontinuous) [](https://fusion.corp.google.com/projectanalysis/current/KOKORO/prod:protobuf%2Fgithub%2Fmaster%2Fmacos%2Fobjectivec_ios_debug%2Fcontinuous) [](https://fusion.corp.google.com/projectanalysis/current/KOKORO/prod:protobuf%2Fgithub%2Fmaster%2Fmacos%2Fobjectivec_ios_release%2Fcontinuous) [](https://fusion.corp.google.com/projectanalysis/current/KOKORO/prod:protobuf%2Fgithub%2Fmaster%2Fmacos%2Fobjectivec_osx%2Fcontinuous) 5 6Copyright 2008 Google Inc. 7 8This directory contains the Objective C Protocol Buffers runtime library. 9 10Requirements 11------------ 12 13The Objective C implementation requires: 14 15- Objective C 2.0 Runtime (32bit & 64bit iOS, 64bit OS X). 16- Xcode 8.0 (or later). 17- The library code does *not* use ARC (for performance reasons), but it all can 18 be called from ARC code. 19 20Installation 21------------ 22 23The distribution pulled from github includes the sources for both the 24compiler (protoc) and the runtime (this directory). After cloning the distribution 25and needed submodules ([see the src directory's README](../src/README.md)), 26to build the compiler and run the runtime tests, you can use: 27 28 $ objectivec/DevTools/full_mac_build.sh 29 30This will generate the `src/protoc` binary. 31 32Building 33-------- 34 35There are two ways to include the Runtime sources in your project: 36 37Add `objectivec/*.h`, `objectivec/google/protobuf/*.pbobjc.h`, and 38`objectivec/GPBProtocolBuffers.m` to your project. 39 40*or* 41 42Add `objectivec/*.h`, `objectivec/google/protobuf/*.pbobjc.h`, 43`objectivec/google/protobuf/*.pbobjc.m`, and `objectivec/*.m` except for 44`objectivec/GPBProtocolBuffers.m` to your project. 45 46 47If the target is using ARC, remember to turn off ARC (`-fno-objc-arc`) for the 48`.m` files. 49 50The files generated by `protoc` for the `*.proto` files (`*.pbobjc.h` and 51`*.pbobjc.m`) are then also added to the target. 52 53Usage 54----- 55 56The objects generated for messages should work like any other Objective C 57object. They are mutable objects, but if you don't change them, they are safe 58to share between threads (similar to passing an NSMutableDictionary between 59threads/queues; as long as no one mutates it, things are fine). 60 61There are a few behaviors worth calling out: 62 63A property that is type NSString\* will never return nil. If the value is 64unset, it will return an empty string (@""). This is inpart to align things 65with the Protocol Buffers spec which says the default for strings is an empty 66string, but also so you can always safely pass them to isEqual:/compare:, etc. 67and have deterministic results. 68 69A property that is type NSData\* also won't return nil, it will return an empty 70data ([NSData data]). The reasoning is the same as for NSString not returning 71nil. 72 73A property that is another GPBMessage class also will not return nil. If the 74field wasn't already set, you will get a instance of the correct class. This 75instance will be a temporary instance unless you mutate it, at which point it 76will be attached to its parent object. We call this pattern *autocreators*. 77Similar to NSString and NSData properties it makes things a little safer when 78using them with isEqual:/etc.; but more importantly, this allows you to write 79code that uses Objective C's property dot notation to walk into nested objects 80and access and/or assign things without having to check that they are not nil 81and create them each step along the way. You can write this: 82 83``` 84- (void)updateRecord:(MyMessage *)msg { 85 ... 86 // Note: You don't have to check subMessage and otherMessage for nil and 87 // alloc/init/assign them back along the way. 88 msg.subMessage.otherMessage.lastName = @"Smith"; 89 ... 90} 91``` 92 93If you want to check if a GPBMessage property is present, there is always as 94`has\[NAME\]` property to go with the main property to check if it is set. 95 96A property that is of an Array or Dictionary type also provides *autocreator* 97behavior and will never return nil. This provides all the same benefits you 98see for the message properties. Again, you can write: 99 100``` 101- (void)updateRecord:(MyMessage *)msg { 102 ... 103 // Note: Just like above, you don't have to check subMessage and otherMessage 104 // for nil and alloc/init/assign them back along the way. You also don't have 105 // to create the siblingsArray, you can safely just append to it. 106 [msg.subMessage.otherMessage.siblingsArray addObject:@"Pat"]; 107 ... 108} 109``` 110 111If you are inspecting a message you got from some other place (server, disk, 112etc), you may want to check if the Array or Dictionary has entries without 113causing it to be created for you. For this, there is always a `\[NAME\]_Count` 114property also provided that can return zero or the real count, but won't trigger 115the creation. 116 117For primitive type fields (ints, floats, bools, enum) in messages defined in a 118`.proto` file that use *proto2* syntax there are conceptual differences between 119having an *explicit* and *default* value. You can always get the value of the 120property. In the case that it hasn't been set you will get the default. In 121cases where you need to know whether it was set explicitly or you are just 122getting the default, you can use the `has\[NAME\]` property. If the value has 123been set, and you want to clear it, you can set the `has\[NAME\]` to `NO`. 124*proto3* syntax messages do away with this concept, thus the default values are 125never included when the message is encoded. 126 127The Objective C classes/enums can be used from Swift code. 128 129Objective C Generator Proto File Options 130---------------------------------------- 131 132**objc_class_prefix=\<prefix\>** (no default) 133 134Since Objective C uses a global namespace for all of its classes, there can 135be collisions. This option provides a prefix that will be added to the Enums 136and Objects (for messages) generated from the proto. Convention is to base 137the prefix on the package the proto is in. 138 139Objective C Generator `protoc` Options 140-------------------------------------- 141 142When generating Objective C code, `protoc` supports a `--objc_opt` argument; the 143argument is comma-delimited name/value pairs (_key=value,key2=value2_). The 144_keys_ are used to change the behavior during generation. The currently 145supported keys are: 146 147 * `generate_for_named_framework`: The `value` used for this key will be used 148 when generating the `#import` statements in the generated code. Instead 149 of being plain `#import "some/path/file.pbobjc.h"` lines, they will be 150 framework based, i.e. - `#import <VALUE/file.pbobjc.h>`. 151 152 _NOTE:_ If this is used with `named_framework_to_proto_path_mappings_path`, 153 then this is effectively the _default_ to use for everything that wasn't 154 mapped by the other. 155 156 * `named_framework_to_proto_path_mappings_path`: The `value` used for this key 157 is a path to a file containing the listing of framework names and proto 158 files. The generator uses this to decide if another proto file referenced 159 should use a framework style import vs. a user level import 160 (`#import <FRAMEWORK/file.pbobjc.h>` vs `#import "dir/file.pbobjc.h"`). 161 162 The format of the file is: 163 * An entry is a line of `frameworkName: file.proto, dir/file2.proto`. 164 * Comments start with `#`. 165 * A comment can go on a line after an entry. 166 (i.e. - `frameworkName: file.proto # comment`) 167 168 Any number of files can be listed for a framework, just separate them with 169 commas. 170 171 There can be multiple lines listing the same frameworkName incase it has a 172 lot of proto files included in it; and having multiple lines makes things 173 easier to read. 174 175Contributing 176------------ 177 178Please make updates to the tests along with changes. If just changing the 179runtime, the Xcode projects can be used to build and run tests. If your change 180also requires changes to the generated code, 181`objectivec/DevTools/full_mac_build.sh` can be used to easily rebuild and test 182changes. Passing `-h` to the script will show the addition options that could 183be useful. 184 185Documentation 186------------- 187 188The complete documentation for Protocol Buffers is available via the 189web at: 190 191 https://developers.google.com/protocol-buffers/ 192
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