The document discusses techniques for improving iOS application build performance and reducing executable size in Xamarin applications. It recommends measuring build times, optimizing for the iOS simulator by avoiding rebuilds and file copying, and optimizing for iOS devices by partially linking assemblies, using the LinkerSafe attribute, and leveraging SmartLink and automatic bindings optimizations. Building configurations and deployment tradeoffs are also covered.

1. Sébastien Pouliot
So!ware Developer
Xamarin
sebastien@xamarin.com
Advanced iOS build mechanics
Improving performance and
reducing executable size

2. Why Should You Care?
Quicker Builds
Smaller Applications
Faster Applications

3. Prime Directive:
Time Everything - Often

4. Best Default Worse
14
7
2
27
19
6
How Much Time? Field Service Sample
Build Time (Debug) Deploy Time
Best Default Worse
37
16
14
169
49
16
Simulator Devices

5. Building for the iOS Simulator
.dll
C#
.exe
+ =
.app
addin
mtouch
•Resolve
•Package
•Embed
mono
•Deploy
?

6. Simulator vs Emulator
• Speed Over Compatibility
• Apple Simulator Tradeoffs
Simpler, less restrictive environment
• Xamarin Simulator Tradeoffs
Just In Time (JIT) compiler
Minimize files copying (symlinks)
Shared application launcher

7. Simulator : What to Do?
best
default 7
2
19
6 Build Time
Deploy Time
• Build
Avoid optimizing PNG files
• Deploy
Keep the simulator running

8. Simulator : What to Avoid?
best
worse 14
2
27
6 Build Time
Deploy Time
• Build
Enabling the linker
Disabling the shared launcher -­‐-­‐nofastsim
• Deploy
Up to 12 seconds to cold start

9. Simulator : Extra Tips
• Prefer Build over Rebuild
• Avoid copying files
Access them from a single location
The sandbox is not enforced
• Use -­‐time
-­‐time to measure your changes

10. -­‐time
-­‐time

11. Building for iOS Devices
•Resolve
•Global
Op8miza8ons
•AOT
Compila8on
•Na8ve
Compila8on
•Na8ve
Linking
•Copy
files
•Op8mize
PNG
•En8tlements
•Code
sign
•IPA
•Symbols
(DWARF)
•Stripping
(symbols)
•Stripping
(IL)
•Packaging
•Deployment
.dll
C#
.exe
+ =
? .app

12. Building for iOS Devices
addin mtouch
•
Resolve
•
Managed
Linking
•
AOT
Compila8on
•
Na8ve
Compila8on
•
Na8ve
Linking
•
Symbols
(DWARF)
•
Copy
files
•
Op8mize
PNG
•
Provisioning
•
En8tlements
•
Code
sign
•
IPA
•
Stripping
•
Registrar
•
IL
Removal
•
Packaging
•
Deploy
apps
•
Install
apps
.dll
C#
.exe
+ =
.app

13. Devices : Build Configurations
• Debug : Keep it quick
• Release : Focus on performance
LLVM Optimizing Compiler
Optimize PNG files
• Ad-Hoc / AppStore : No tweaks!

14. Build & Deploy Symbiosis
• Deployment time is a function of the app size
• Application size versus build time?
• Link SDK is default for devices

15. Devices : What to Do?
best
default 16
14
49
16 Build Time
Deploy Time
• Build
Avoid optimizing PNG files (debug)
• Consider
Linking all assemblies --linkall
Disabling the symbols creation --dsym=false

16. Devices : What to Avoid?
best
worse 37
14
169
16 Build Time
Deploy Time
• FAT binaries (debug)
• Disabling the linker --nolink
• Disabling stripping
Symbols --nosymbolstrip
IL (release) --nostrip

17. Devices : Extra Tips
• Prefer Build over Rebuild
AOT’ed assemblies (object files) are cached
• Avoid deploying large static files (debug)
Use UIFileSharingEnabled (Info.plist)
• Use -­‐time
-­‐time to measure your changes

18. -­‐time
-­‐time -­‐dsym=false

20. Beyond Build Tips

21. It’s a Matter of Time and Size
Don’t Link
Link SDK
Link All 9
10
20
21
23
89
Build Time Deploy Time
48.6 MB
11.5 MB
10.9 MB
Field
Service
Sample
Applica8on*
*
Release
build,
LLVM,
ARMv7

22. 01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
Static Analysis Limitations
...
using
FieldService.Utilities;
#if
__iOS__
using
MonoTouch.Foundation;
#elif
__ANDROID__
using
Android.Runtime;
#endif
namespace
FieldService.Data
{
///
<summary>An
assignment
is
the
"thing"
or
"job"
the
user
is
going...
#if
!MOBILE
[Preserve
(AllMembers
=
true)]
#endif
public
class
Assignment
{
...
}

23. 01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
Static Analysis Limitations
<!-­‐-­‐
add
`-­‐-­‐xml=field.service.xml`
to
your
project
options
-­‐-­‐>
<linker>
<assembly
fullname="FieldServiceiOS">
<type
fullname="FieldService.Data.Assignment"
/>
<type
fullname="FieldService.Data.AssignmentHistory"
/>
<type
fullname="FieldService.Data.AssignmentItem"
/>
<type
fullname="FieldService.Data.Document"
/>
<type
fullname="FieldService.Data.Expense"
/>
<type
fullname="FieldService.Data.ExpensePhoto"
/>
<type
fullname="FieldService.Data.Preserve"
/>
<type
fullname="FieldService.Data.Labor"
/>
<type
fullname="FieldService.Data.Photo"
/>
<type
fullname="FieldService.Data.Signature"
/>
<type
fullname="FieldService.Data.TimeEntry"
/>
</assembly>
</linker>

24. Partially Linking Applications
• Link All and skip some assemblies
No source required
e.g. -­‐-­‐linkall
-­‐-­‐linkskip=FieldServiceiOS
• Link SDK and use [LinkerSafe] attribute
Source code required

25. Objective-C Bindings
• Cocos2d’s Jumpy saves 409 KB using
[assembly:LinkerSafe]
• Less [Export] means faster registration

26. SmartLink
• New option [LinkWith
(SmartLink=true)]
and -­‐-­‐registrar=static
• Helps the native linker
DropBox’s Sync samples drops by 325KB

27. 01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
[Export
("sizeToFit")]
void
SizeToFit
();
[Export
("sizeToFit")]
[CompilerGenerated]
public
virtual
void
SizeToFit
()
{
global::MonoTouch.UIKit.UIApplication.EnsureUIThread
();
if
(IsDirectBinding)
{
Messaging.void_objc_msgSend
(this.Handle,
Selector.GetHandle
("sizeToFit"));
}
else
{
Messaging.void_objc_msgSendSuper
(this.SuperHandle,
Selector.GetHandle
("sizeToFit"));
}
}
Automatic Bindings Optimizations
[Export
("sizeToFit")]
void
SizeToFit
();
[Export
("sizeToFit")]
[CompilerGenerated]
public
virtual
void
SizeToFit
()
{
global::MonoTouch.UIKit.UIApplication.EnsureUIThread
();
if
(IsDirectBinding)
{
Messaging.void_objc_msgSend
(this.Handle,
Selector.GetHandle
("sizeToFit"));
}
else
{
Messaging.void_objc_msgSendSuper
(this.SuperHandle,
Selector.GetHandle
("sizeToFit"));
}
}

28. 01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
System.Drawing.SizeF
ret;
if
(IsDirectBinding)
{
if
(Runtime.Arch
==
Arch.DEVICE)
{
Messaging.SizeF_objc_msgSend_stret
(out
ret,
this.Handle,
...
}
else
{
ret
=
Messaging.SizeF_objc_msgSend
(this.Handle,
...
}
}
else
{
if
(Runtime.Arch
==
Arch.DEVICE)
{
Messaging.SizeF_objc_msgSendSuper_stret
(out
ret,
...
}
else
{
ret
=
Messaging.SizeF_objc_msgSendSuper
(this.SuperHandle,
...
}
}
return
ret;
Automatic Bindings Optimizations
System.Drawing.SizeF
ret;
if
(IsDirectBinding)
{
if
(Runtime.Arch
==
Arch.DEVICE)
{
Messaging.SizeF_objc_msgSend_stret
(out
ret,
this.Handle,
...
}
else
{
ret
=
Messaging.SizeF_objc_msgSend
(this.Handle,
...
}
}
else
{
if
(Runtime.Arch
==
Arch.DEVICE)
{
Messaging.SizeF_objc_msgSendSuper_stret
(out
ret,
...
}
else
{
ret
=
Messaging.SizeF_objc_msgSendSuper
(this.SuperHandle,
...
}
}
return
ret;

29. 01
02
03
04
05
06
07
08
09
10
11
12
13
14
15
16
Automatic Bindings Optimizations
object
__mt_RootViewController_var;
[CompilerGenerated]
public
virtual
UIViewController
RootViewController
{
[Export
("rootViewController",
ArgumentSemantic.Retain)]
get
{
global::MonoTouch.UIKit.UIApplication.EnsureUIThread
();
UIViewController
ret;
if
(IsDirectBinding)
{
ret
=
(UIViewController)
Runtime.GetNSObject
(...
msgSend
...);
}
else
{
ret
=
(UIViewController)
Runtime.GetNSObject
(...
msgSendSuper
...);
}
if
(!IsNewRefcountEnabled
())
__mt_RootViewController_var
=
ret;
return
ret;
}
...
object
__mt_RootViewController_var;
[CompilerGenerated]
public
virtual
UIViewController
RootViewController
{
[Export
("rootViewController",
ArgumentSemantic.Retain)]
get
{
global::MonoTouch.UIKit.UIApplication.EnsureUIThread
();
UIViewController
ret;
if
(IsDirectBinding)
{
ret
=
(UIViewController)
Runtime.GetNSObject
(...
msgSend
...);
}
else
{
ret
=
(UIViewController)
Runtime.GetNSObject
(...
msgSendSuper
...);
}
if
(!IsNewRefcountEnabled
())
__mt_RootViewController_var
=
ret;
return
ret;
}
...
object
__mt_RootViewController_var;
[CompilerGenerated]
public
virtual
UIViewController
RootViewController
{
[Export
("rootViewController",
ArgumentSemantic.Retain)]
get
{
global::MonoTouch.UIKit.UIApplication.EnsureUIThread
();
UIViewController
ret;
if
(IsDirectBinding)
{
ret
=
(UIViewController)
Runtime.GetNSObject
(...
msgSend
...);
}
else
{
ret
=
(UIViewController)
Runtime.GetNSObject
(...
msgSendSuper
...);
}
if
(!IsNewRefcountEnabled
())
__mt_RootViewController_var
=
ret;
return
ret;
}
...

30. Quicker builds
Smaller apps
Faster apps

31. Q&A

32. THANK YOU
related links @ http://bit.ly/ios-build