statically linked modules are fastest to load (loading non-system dynamic frameworks is pretty expensive while system frameworks are optimized). When using static linking, all the symbols are within the same module, so the app start is fast. dynamically linked modules are slower to load, especially on iOS.
A dynamic framework is a bundle of code loaded into an executable at runtime, instead of at compile time. Examples in iOS include UIKit and the Foundation frameworks. Frameworks such as these contain a dynamic library and optionally assets, such as images.
Static frameworks contain a static library packaged with its resources. Dynamic frameworks contain the dynamic library with its resources. In addition to that, dynamic frameworks may conveniently include different versions of the same dynamic library in the same framework!
It can be either. Only iOS8+ will allow dynamic frameworks in the app bundle, however. Where ar archive means "static library". Alternatively, a "dynamic" framework will look like this and explicitly state that it's dynamically linked.
It can be either.
Only iOS8+ will allow dynamic frameworks in the app bundle, however.
The way to find out is to look in the .framework
and use the file
command on the main file:
$ cd iOS/Crashlytics.framework
$ ls -l
total 9984
-rwxr-xr-x 1 andy staff 4710656 11 Sep 17:11 Crashlytics
drwxr-xr-x 8 andy staff 272 11 Sep 17:11 Headers
-rw-r--r-- 1 andy staff 1553 11 Sep 17:11 Info.plist
drwxr-xr-x 3 andy staff 102 11 Sep 17:11 Modules
-rwxr-xr-x 1 andy staff 146164 11 Sep 17:11 run
-rwxr-xr-x 1 andy staff 241688 11 Sep 17:11 submit
$ file Crashlytics
Crashlytics: Mach-O universal binary with 5 architectures
Crashlytics (for architecture armv7): current ar archive random library
Crashlytics (for architecture armv7s): current ar archive random library
Crashlytics (for architecture i386): current ar archive random library
Crashlytics (for architecture x86_64): current ar archive random library
Crashlytics (for architecture arm64): current ar archive random library
Where ar archive
means "static library".
Alternatively, a "dynamic" framework will look like this and explicitly state that it's dynamically linked.
$ cd /Library/Frameworks/iTunesLibrary.framework/
$ ls -l
total 40
lrwxr-xr-x 1 root wheel 24 10 Sep 17:38 Headers -> Versions/Current/Headers
lrwxr-xr-x 1 root wheel 24 10 Sep 17:38 Modules -> Versions/Current/Modules
lrwxr-xr-x 1 root wheel 26 10 Sep 17:38 Resources -> Versions/Current/Resources
drwxr-xr-x 4 root wheel 136 10 Sep 17:41 Versions
lrwxr-xr-x 1 root wheel 22 10 Sep 17:38 XPCServices -> Versions/A/XPCServices
lrwxr-xr-x 1 root wheel 30 10 Sep 17:38 iTunesLibrary -> Versions/Current/iTunesLibrary
$ file Versions/Current/iTunesLibrary
Versions/Current/iTunesLibrary: Mach-O universal binary with 2 architectures
Versions/Current/iTunesLibrary (for architecture i386): Mach-O dynamically linked shared library i386
Versions/Current/iTunesLibrary (for architecture x86_64): Mach-O 64-bit dynamically linked shared library x86_64
I use this command to list all STATIC Frameworks from a path with a list of frameworks:
find -E . -type f -iregex ".*\.framework\/[^./]*" -exec file {} \; | grep ': current ar archive' | sed 's/.*\/\(.*.framework\).*/\1/'
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