[swift-users] Swift Binary Size vs. Obj-C

[Austin Zheng]

Sorry, I totally missed the part where you mentioned the runtime libs.

I assume you're compiling your Objective-C code using the `-Os`
optimization level? Unfortunately, it doesn't seem like swiftc has any
flags for trading off speed and binary size. Part of the size discrepancy
is almost certainly due to the immaturity of the compiler.

This is probably only valid for the roughest of OOM estimates, but
LinkedIn's iOS app is 135 MB (don't know how it breaks down in terms of
assets vs code), and is almost entirely implemented in Swift. It's not much
to go off, but it might provide you with a starting point.

If any of your company's engineers are at WWDC, you might want to have them
ask the engineers during the developer tools labs.

Best,
Austin


On Wed, Jun 15, 2016 at 5:16 PM, Seth Friedman via swift-users <
swift-users at swift.org> wrote:

> Thanks for the quick reply. You guys are right on part of it; the runtime
> libraries are causing the majority of the increase. I thought the Swift
> runtime libraries were supposed to only take up 4.5 MB though? Did they
> increase with Swift 3? If I add up all of the libraries, they take up a
> total of 22.88 MB in the binary. About how big would they be if I had
> Bitcode turned on?
>
> That said, the actual Swift binary is still larger. In my table view
> example, the Objective-C binary is 144 KB and the Swift binary is 201 KB. *That's
> still a 40% increase*. Obviously it's much harder to test a large-scale
> app, but I'd like to know the percentage increase to expect if we were to
> migrate to Swift.
>
> On Wed, Jun 15, 2016 at 5:04 PM Saagar Jha <saagarjha28 at gmail.com> wrote:
>
>> Yep, I just took a simple app and opened up the ipa. 90% of it is the
>> “Frameworks” directory containing the Swift frameworks libSwiftCore.dylib,
>> libSwiftDarwin.dylib, etc.
>>
>>
>> On Wed, Jun 15, 2016 at 3:43 PM Seth Friedman via swift-users <
>> swift-users at swift.org> wrote:
>>
>>> Hi all,
>>>
>>> I've seen a ton of blog posts written about all of the cool and exciting
>>> things about Swift, but I haven't see anything really about the downsides
>>> (besides the occasional post about pain points with interoperability).
>>> What's of biggest concern to me when considering migrating my company's app
>>> from Objective-C to Swift is binary size. Swift binary size seems to be
>>> several times larger than Objective-C, and I'm curious what data there is
>>> in the community to support this suspicion.
>>>
>>> For some quick data points, I created a single view controller project
>>> in Obj-C and one in Swift, turned off bitcode to get a better idea of what
>>> the binary size on device would be, and archived them. I did this in Xcode
>>> 8 Beta 1 using Swift 3 so that I'd make sure to get any binary size
>>> improvements in Swift 3.
>>>
>>> The Obj-C IPA file was 639 KB. The Swift IPA file was *23.6 MB*. I know
>>> that the Swift runtime libs are about 4.5 MB, but subtracting that, the
>>> Swift IPA file is still *30x bigger than the Obj-C equivalent*. Next, I
>>> tried adding a simple table view controller, a Person model with a first
>>> and last name, and a data source that puts the first and last names in the
>>> table view in an attempt to make a functioning app. However, the binary
>>> sizes were about the same (the Obj-C one actually decreased to 635 KB).
>>>
>>> When we're talking about binary sizes this small, it's not a big deal,
>>> but my company's app is currently 81 MB, about 35 MB of which is code, and
>>> the rest is assets. If the code part of the binary size increases by orders
>>> of magnitude like this, we'll go way over the 100 MB cellular limit that
>>> Apple has set. This is also a really bad experience for customers in
>>> emerging markets like China and India that have poor connections.
>>>
>>> Can anyone confirm or deny that Swift binary size is orders of magnitude
>>> larger than Objective-C? I'm looking for the specific increase we'll see to
>>> take to my management in order to make a justification for whether it's
>>> worth it for our customers.
>>>
>>> Thanks!
>>>
>>> Seth Friedman
>>>
>>>
>>> _______________________________________________
>>> swift-users mailing list
>>> swift-users at swift.org
>>> https://lists.swift.org/mailman/listinfo/swift-users
>>>
>> --
>> -Saagar Jha
>>
>
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