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

[Seth Friedman]

Does anyone know if the runtime libs definitively increased in size in
Swift 3? I could have sworn I heard 4.5 MB for Swift 2.

Also, does anyone know if there are plans to introduce a `-Os` equivalent
for Swift? (Yes, I'm using that in Obj-C, to answer your question).

Thanks!

Seth

On Wed, Jun 15, 2016 at 5:27 PM Austin Zheng <austinzheng at gmail.com> wrote:

> 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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