Like Rick, I had also wondered about a simple way to do this. Perhaps this is a
question for swift-evolution, but wouldn’t it be desirable if Swift supported:
for item in someOptionalContainer?
{
}
which seems more natural and intuitive that the alternatives that have been
suggested.
Kerry
> On Jul 28, 2016, at 5:18 PM, Zhao Xin via swift-users <swift-users@swift.org>
> wrote:
>
> You can try container?.forEach(), like
>
> let bb:[String:Int]? = ["aa":1, "bb":2, "cc":3]
> bb?.forEach { print($0) }
> /*
> ("aa", 1)
> ("bb", 2)
> ("cc", 3)
> */
>
> Zhaoxin
>
> On Fri, Jul 29, 2016 at 6:14 AM, Saagar Jha via swift-users
> <swift-users@swift.org <mailto:swift-users@swift.org>> wrote:
> The nil check and creating an empty array have very similar performance, in
> my naïve testing.
>
> Saagar Jha
>
>
>
>> On Jul 28, 2016, at 14:59, Jacob Bandes-Storch via swift-users
>> <swift-users@swift.org <mailto:swift-users@swift.org>> wrote:
>>
>> You should test it out — I'd guess there's a good chance it gets optimized
>> out.
>> On Thu, Jul 28, 2016 at 2:58 PM Rick Mann <rm...@latencyzero.com
>> <mailto:rm...@latencyzero.com>> wrote:
>> Yeah, I suppose that works. Feels a bit clunky, like the language lacks
>> specific support for this (in that it provides specific support for so many
>> other common constructs). But I guess I can make do with that.
>>
>> I suppose there's a bit of a performance hit, in that constructing an empty
>> array and iterating over it is more expensive than a simple nil check, but
>> that's unlikely to cause issues in practice.
>>
>> Thanks.
>>
>> > On Jul 28, 2016, at 14:56 , Jacob Bandes-Storch <jtban...@gmail.com
>> > <mailto:jtban...@gmail.com>> wrote:
>> >
>> > How about "for item in someOptionalContainer ?? []" ?
>> >
>> > On Thu, Jul 28, 2016 at 2:55 PM, Rick Mann via swift-users
>> > <swift-users@swift.org <mailto:swift-users@swift.org>> wrote:
>> > I often call methods that return an optional collection. I then iterate
>> > over it. The problem is, it's a bit cumbersome to write:
>> >
>> > if let container = someOptionalContainer
>> > {
>> > for item in container
>> > {
>> > }
>> > }
>> >
>> > I wish I could just write
>> >
>> > for item in someOptionalContainer
>> > {
>> > }
>> >
>> > such that if the optional is nil, it just skips the iteration altogether.
>> >
>> > Is there a syntax for that (especially in Swift 3)?
>> >
>> >
>> > --
>> > Rick Mann
>> > rm...@latencyzero.com <mailto:rm...@latencyzero.com>
>> >
>> >
>> > _______________________________________________
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>> > swift-users@swift.org <mailto:swift-users@swift.org>
>> > https://lists.swift.org/mailman/listinfo/swift-users
>> > <https://lists.swift.org/mailman/listinfo/swift-users>
>> >
>>
>>
>> --
>> Rick Mann
>> rm...@latencyzero.com <mailto:rm...@latencyzero.com>
>>
>>
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