Youtube iOS app is a high-rating video streaming app. It is absolutely 5 stars. For me with the experience I have gained in the iOs mobile app development, I have to say that the youtube iOS app is kinda a role model in the industry. It successfully gives the end-users the best experience. The app is smooth, high responsive, stable, simple and well-designed generally.
In this post, I’m gonna share what I have seen inside the latest Youtube IPA package file. As you guys have known, on iOS the IPA file is the final package which reach to the end customers. By looking over this file, I think it’s gonna reveal many things many questions.
I pulled the latest IPA file from my phone at Mar 5 2019. In order to save your time, you can just go to iphonecake.com and grab the file
Open source, 3rd party libs
The thing I pay most attention is there are a lot of software license files in the package/ These are maybe the clues on the technologies and libs which the app used. Below is the list. I have categorized them, but I still feel overwhelm because most of them are not in my awareness. How many of them you haven known and not known? Ok, Check them out.
- Image processing, Graphical lib
GL_LICENSE.html -> This maybe is open GL library
glm_LICENSE.html -> glm – OpenGL mathematics library
openctm_LICENSE.html -> openctm – OpenCTM is a file format, a software library and a tool set for compression of 3D triangle meshes
OpenCV_LICENSE.html -> OpenCV – computer vision lib
OpenCVX_LICENSE.html -> OpenCVX – computer vision extensions lib
drishti_LICENSE.html -> Drishti – eye tracking lib
swiftshader_LICENSE.html -> SwiftShader – high-performance CPU-based implementation of the OpenGL ES and Direct3D 9 graphics APIs
lullaby_LICENSE.html -> Google lullaby – A collection of C++ libraries designed to help teams develop virtual and augmented reality experiences
libtxc_dxtn_LICENSE.html -> libtxc_dxtn – Helper library for S3TC texture (de)compression - Algorithm
absl_algorithm_LICENSE.html -> Abseil – General C++ lib
dimsum_LICENSE.html -> Google Dimsum – General C++ lib
stblib_LICENSE.html -> stblib – stb single-file public domain libraries for C/C++
address_sorting_LICENSE.html -> address_sorting (not sure about the source)
eigen3_LICENSE.html -> Eigen 3 – C++ template library for linear algebra: matrices, vectors, numerical solvers, and related algorithms.
gemmlowp_LICENSE.html -> gemmlowp – general matrix multiplication C++ lib
kissfft_LICENSE.html -> Kiss FFT – Fast Fourier Transform (FFT) C++ library
lapack_LICENSE.html -> LAPACK (not sure about this)
half_LICENSE.html -> HALF-PRECISION FLOATING POINT LIBRARY
vectorial_LICENSE.html -> vectorial – Vector math library
pcg_random_LICENSE.html/PCG Random Number Generator - Encryption
crunchy_LICENSE.html -> Google Crunchy Crypt
highwayhash_LICENSE.html -> Google HighwayHash – Fast strong hash functions: SipHash/HighwayHash - Networking – Data transport
android_nanoproto_LICENSE.html -> Protobuf Nano (not sure about the source)
ares_LICENSE.html -> ares – A C library for asynchronous DNS requests
curl_LICENSE.html -> curl – A command line tool and library for transferring data
libevent_LICENSE.html -> libevent – an event notification library
grpc_LICENSE.html -> gRPC – Google universal RPC framework
openssl_LICENSE.html -> Google BoringSSL – BoringSSL is a fork of OpenSSL that is designed to meet Google’s needs.
grte_extensions_LICENSE.html/GRTE
protobuf_LICENSE.html -> Protocol Buffers – Google’s language-neutral, platform-neutral, extensible mechanism for serializing structured data – think XML, but smaller, faster, and simpler
flatbuffers_LICENSE.html -> Google FlatBuffers – cross platform serialization library for multi languages
libsrtp_LICENSE.html -> Cisco libSRTP – Secure Realtime Transport Protocol
nanopb_LICENSE.html -> Nanopb – Protocol Buffers with small code size - Parser
libxml_LICENSE.html -> Libxml2 – XML C parser and toolkit
tinyxml2_LICENSE.html -> tinyxml2
xmpmeta_LICENSE.html -> Google xmpmeta – library for parsing and writing XMP and XDM metadata
yaml_cpp_LICENSE.html -> yaml_cpp – A YAML parser and emitter in C++
uri_parser_LICENSE.html -> uri_parser – a strictly RFC 3986 compliant URI parsing and handling library written in C - Chromium
breakpad_LICENSE.html -> breakpad (not sure about the source)
chromium_certificate_verifier_LICENSE.html -> Chrome Certificate Verifier (not sure about the source)
chromium_media_parsers_LICENSE.html -> chromium_media_parsers (not sure about the source) - Compression
brotli_LICENSE.html -> Google Brotli – Brotli compression format
bz2lib_LICENSE.html -> bzip2 – file compression program
minizip_LICENSE.html -> minizip -Minizip framework wrapper
zippy_LICENSE.html -> Zippy (not source about the source)
zlib_LICENSE.html -> zlib – lossless data-compression library
zstdlib_LICENSE.html -> Zstandard – real-time compression algorithm - Javascript
v8_v6_9_LICENSE.html -> V8 v6.9 – Google’s open source high-performance JavaScript and WebAssembly engine, written in C++
gios_closure_compiler_LICENSE.html -> Closure Compiler – A JavaScript checker and optimizer.
gios_closure_library_LICENSE.html -> Closure Library -mGoogle’s common JavaScript library
javascript_jquery2_LICENSE.html -> jquery2
javascript_jquery_ui_LICENSE.html -> jquery_ui
javascript_tracing_framework_LICENSE.html -> Google tracing_framework – A powerful toolset for investigating the performance of rich Javascript applications. - Java, android
java_src_j2objc_protobuf_LICENSE.html -> Google J2ObjC – A Java to iOS Objective-C translation tool and runtime - Others
darts_clone_LICENSE.html
halide_LICENSE.html -> Halide – a language for fast, portable data-parallel computation
lua_LICENSE.html -> lua (not sure about the source)
- Video, Image, Codec
dav1d_LICENSE.html -> dav1d – AV1 decoder
libyuv_LICENSE.html -> libyuv – YUV scaling and conversion functionality
jpeg_LICENSE.html -> libjpeg – JPEG image codec lib
lodepng_LICENSE.html -> lodepng – PNG image decoder and encoder standalone lib
libjpeg_turbo_LICENSE.html -> libjpeg-turbo – JPEG image codec
png_LICENSE.html/PNG
tiff_LICENSE.html - Google SDK, API
firebase_ios_Releases_FirebaseCore_LICENSE.html -> Firebase
googleurl_LICENSE.html/googleurl - Text, String, Font
freetype2_LICENSE.html -> freetype2 – render fonts lib
utf_LICENSE.html -> UTF – handle UTF-8 encoded Unicode strings
icu_LICENSE.html -> ICU4C – International Components for Unicode
pcre_LICENSE.html -> PCRE – regular expression pattern
re2_LICENSE.html -> RE2 – a regular expression library
unsmear_LICENSE.html -> Unsmear - Game
fplbase_LICENSE.html -> Google fplbase – lowest level game library
mathfu_LICENSE.html -> Google mathfu – C++ math library developed primarily for games
motive_LICENSE.html -> Google motive – an animation system written in cross-platform C++
fplutil_libfplutil_LICENSE.html -> Google libfplutil – fplutil is a set of small libraries and tools that can be useful when developing applications for Android and other platforms - Speech, audio
speex_v1_2rc1_LICENSE.html -> speex – patent-free audio compression format designed for speech
stl_LICENSE.html -> STL – speech and audio-related speech processing
libresample_LICENSE.html -> libresample – Real-time library for sample rate conversion
libopus_LICENSE.html -> Opus audio codec – Utility, Encode, decode Ogg Opus files (not sure about the source) - Machine learning, neural network
tensorflow_LICENSE.html -> TensorFlow
rnnoise_LICENSE.html -> rnnoise – Recurrent neural network for audio noise reduction - Objective-C
objective_c_AppleReachability_LICENSE.html -> AppleReachability
objective_c_ChromeWebView_LICENSE.html -> ChromeWebView
objective_c_CocoaHTTPServer_LICENSE.html -> CocoaHTTPServer – A small, lightweight, embeddable HTTP server
objective_c_CocoaLumberJack_LICENSE.html -> CocoaLumberJack – A fast & simple, yet powerful & flexible logging framework
objective_c_Cronet_LICENSE.html -> Chromium Cronet – Cronet is the networking stack of Chromium put into a library for use on mobile
objective_c_DTCoreText_Externals_DTFoundation_LICENSE.html -> DTFoundation – Standard toolset classes and categories
objective_c_DTCoreText_LICENSE.html -> DTCoreText – Methods to allow using HTML code with CoreText
objective_c_FLAnimatedImage_LICENSE.html -> Flipboard – FLAnimatedImage – Performant animated GIF engine for iOS
objective_c_IGListKit_LICENSE.html -> Instagram InstragIGListKit – A data-driven UICollectionView framework
objective_c_OALayoutAnchor_LICENSE.html -> OALayoutAnchor
objective_c_OAStackView_LICENSE.html -> OAStackView – Porting UIStackView to iOS 7+
objective_c_ObjectionFramework_LICENSE.html -> ObjectionFramework – A lightweight dependency injection framework for Objective-C
objective_c_PINCache_LICENSE.html -> Pinterest PINCache – Fast, non-deadlocking parallel object cache
objective_c_PINOperation_LICENSE.html -> Pinterest PINOperation – Fast, concurrency-limited task queue
objective_c_PINRemoteImage_LICENSE.html -> Pinterest PINRemoteImage – A thread safe, performant, feature rich image fetcher
objective_c_Promises_LICENSE.html -> promise kit | Google promises (not sure about the source)
objective_c_ResumableAssert_LICENSE.html -> Google ResumableAssert – Assert replacement to continue execution in debugger
objective_c_TBXML_LICENSE.html -> TBXML – Super-fast, lightweight, easy to use XML parser
objective_c_TPCircularBuffer_LICENSE.html -> TPCircularBuffer – A simple, fast circular buffer implementation for audio processing
objective_c_Texture_LICENSE.html -> Facebook Texture – Asynckit for smooth asynchronous user interfaces
objective_c_VideoCore_LICENSE.html -> VideoCore – video manipulation and streaming graph
objective_c_google_api_objectivec_client_for_rest_LICENSE.html -> Google APIs Client Library for Objective-C for REST
objective_c_google_toolbox_for_mac_LICENSE.html -> Google Toolbox for Mac
objective_c_gtm_session_fetcher_LICENSE.html -> Google gtm_session_fetcher
objective_c_libPhoneNumber_iOS_LICENSE.html -> libPhoneNumber_iOS
objective_c_lottie_ios_LICENSE.html ->Airbnb lottie_ios – iOS library to natively render After Effects vector animations
yoga_LICENSE.html -> Facebook yoga – a cross-platform layout engine which implements FlexboxMaterial.io
objective_c_material_components_ios_LICENSE.html -> Material.io Components for iOS
objective_c_material_font_disk_loader_ios_LICENSE.html -> Material.io MDFFontDiskLoader
objective_c_material_internationalization_ios_LICENSE.html -> Marerial.io MDFInternationalization
objective_c_material_roboto_font_loader_ios_LICENSE.html -> Material.io MDFRobotoFontLoader
objective_c_material_sprited_animation_view_ios_LICENSE.html -> Material.io MDFSpritedAnimationView
objective_c_material_text_accessibility_ios_LICENSE.html -> Material.io MDFTextAccessibility
objective_c_motion_animator_LICENSE.html -> Material – motion animator
objective_c_motion_interchange_LICENSE.html -> Material – motion interchange
objective_c_motion_transitioning_LICENSE.html -> Material – motion transitioning
objective_c_nimbus_LICENSE.html -> nimbus - Debugging
tracing_framework_bindings_cpp_LICENSE.html -> Web Tracing Framework C++ Bindings - RTC
webrtc_LICENSE.html -> WebRTC – Real-Time Communications (RTC) capabilities via simple APIs
webrtc_files_stable_webrtc_common_audio_third_party_fft4g_LICENSE.html/fft4g
webrtc_files_stable_webrtc_common_audio_third_party_spl_sqrt_floor_LICENSE.html/spl_sqrt_floor
webrtc_files_stable_webrtc_examples_androidapp_third_party_autobanh_LICENSE.html/AutobahnAndroid
webrtc_files_stable_webrtc_modules_third_party_fft_LICENSE.html/fft
webrtc_files_stable_webrtc_modules_third_party_g711_LICENSE.html/g771
webrtc_files_stable_webrtc_modules_third_party_g722_LICENSE.html/g722
webrtc_files_stable_webrtc_modules_third_party_portaudio_LICENSE.html/Portaudio
webrtc_files_stable_webrtc_rtc_base_third_party_base64_LICENSE.html/Base64
webrtc_files_stable_webrtc_rtc_base_third_party_sigslot_LICENSE.html/sigslot - Unclassified
OpenBLAS_LICENSE.html -> OpenBLAS
SADIE_hrtf_database_LICENSE.html
Xorg_LICENSE.html -> X.Org
cbc_LICENSE.html -> cbc (not sure about the source)
astc_codec_LICENSE.html -> Google astc_codec – ASTC decoder
usrsctp_LICENSE.html -> SCTP – A portable SCTP userland stackcloud_truetime_c_sequence_lock_LICENSE.html
fft2d_LICENSE.html/Ooura FFT (not sure about the source)
libcap_LICENSE.html -> The libcap package implements the user-space interfaces to the POSIX (Not sure this lib is used for what)
intel_intrinsics_LICENSE.html – not sure about this, but there is an explain
pffft_LICENSE.html -> pffft – A Parallel Portable Library for Computing FFT
libffi_LICENSE.html -> libffi – FFI stands for Foreign Function Interface. A foreign function interface is the popular name for the interface that allows code written in one language to call code written in another language
mesa_LICENSE.html -> mesa – an agent-based modeling framework in Python
mongoose_LICENSE.html -> mongoose – GitHub’s most popular embedded web server
After going through the list of the open source and 3rd libraries which the Youtube app has used. I’m so surprised on these things:
- The number of libraries It has consumed is massive (~150 open source / 3rd party libs) if comparing to some enterprise apps I have known and developed. I’m not sure how many of them Youtube actually has consumed, but the number is impressive.
- Youtube team is not shy away on using open source libs. Some of open source lib are not even high rated.
- Youtube team is not afraid to use the open source libs from its competitors. For examples: Facebook, Instagram, Pinterest.
- Youtube/ Google has built its in-house libraries, and it’s willing to open them for everyone as well.
Programming Language
By what I have seen in the IPA file, I believe the app has been written in Objective-C, because of these:
- There are clues which show that the app has consumed many Objective-C open source libs.
- The app seems like consuming a lot of C/C++ libs, so Objective-C is a more appropriate choice.
- There is no sight of a dynamic frameworks because the frameworks directory is almost empty.
Conclusion
To keep this post short and not so overwhelming, I should stop it here. I think it may reveal some of your questions. Actually I feel happy because it also has answered some of my questions:
- I feel a little bit supprise because one the most giant tech like Youtube/Google has use open source and 3rd libraries. It does and it uses massively. This can be a good strategy to not build everything again from scratch like somebody says “Don’t re-invent the wheel”, otherwise it is time-consuming, money-consuming and the output may not be better. Some 3rd library has been mature, and used widely for decades.
- This IPA package shows us that Objective-C has been using. Objective-C is still a good programming language to rely on.
In the next post, I’m going to analyze the Youtube app structure, its view layout and the floating video player in it. Check it out here
