<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><br class=""><div><blockquote type="cite" class=""><div class="">On Oct 5, 2016, at 2:30 AM, Lars-Jørgen Kristiansen via swift-users <<a href="mailto:swift-users@swift.org" class="">swift-users@swift.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><meta http-equiv="Content-Type" content="text/html charset=us-ascii" class=""><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class="">I'm working with a third party API for some external hardware. One of the functions takes a NSNumber, and it fails to interact correctly with the hardware if I cast a Float too NSNumber, but works as expected if I use Double..</div><div class=""><br class=""></div>I dont know if it is related to NSNumber.stringValue since I dont know what the third part lib does with the NSNumber, but I noticed this:<div class=""><div class=""><div class=""><br class=""></div><div class=""><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; color: rgb(39, 42, 216);" class=""><div style="margin: 0px; line-height: normal;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">let</span><span style="font-variant-ligatures: no-common-ligatures" class=""> float = </span><span style="font-variant-ligatures: no-common-ligatures; color: #272ad8" class="">100_000_00</span><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">as</span><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Float</span></div><div style="margin: 0px; line-height: normal;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">let</span><span style="font-variant-ligatures: no-common-ligatures" class=""> floatNumber = </span><span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">float</span><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">as</span><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">NSNumber</span></div><div style="margin: 0px; line-height: normal; min-height: 13px;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""></span><br class=""></div><div style="margin: 0px; line-height: normal;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">let</span><span style="font-variant-ligatures: no-common-ligatures" class=""> double = </span><span style="font-variant-ligatures: no-common-ligatures; color: #272ad8" class="">100_000_00</span><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">as</span><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">Double</span></div><div style="margin: 0px; line-height: normal;" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">let</span><span style="font-variant-ligatures: no-common-ligatures" class=""> doubleNumer = </span><span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">double</span><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">as</span><span style="font-variant-ligatures: no-common-ligatures" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">NSNumber</span></div><div style="margin: 0px; line-height: normal; min-height: 13px;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""></span><br class=""></div><div style="margin: 0px; line-height: normal; color: rgb(0, 132, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">hardware</span><span style="font-variant-ligatures: no-common-ligatures;" class="">.</span><span style="font-variant-ligatures: no-common-ligatures; color: #31595d" class="">doThing</span><span style="font-variant-ligatures: no-common-ligatures;" class="">(number: </span><span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">floatNumber</span><span style="font-variant-ligatures: no-common-ligatures;" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">as</span><span style="font-variant-ligatures: no-common-ligatures;" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">NSNumber</span><span style="font-variant-ligatures: no-common-ligatures;" class="">) </span><span style="font-variant-ligatures: no-common-ligatures" class="">// Hardware does not work</span></div><div style="margin: 0px; line-height: normal; color: rgb(79, 129, 135);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">hardware</span><span style="font-variant-ligatures: no-common-ligatures;" class="">.</span><span style="font-variant-ligatures: no-common-ligatures; color: #31595d" class="">doThing</span><span style="font-variant-ligatures: no-common-ligatures;" class="">(number: </span><span style="font-variant-ligatures: no-common-ligatures" class="">doubleNumer</span><span style="font-variant-ligatures: no-common-ligatures;" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #ba2da2" class="">as</span><span style="font-variant-ligatures: no-common-ligatures;" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #703daa" class="">NSNumber</span><span style="font-variant-ligatures: no-common-ligatures;" class="">) </span><span style="font-variant-ligatures: no-common-ligatures; color: #008400" class="">// Hardware works</span></div><div style="margin: 0px; line-height: normal; min-height: 13px;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""></span><br class=""></div><div style="margin: 0px; line-height: normal; color: rgb(0, 132, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">// Also noticed this:</span></div><div style="margin: 0px; line-height: normal; color: rgb(79, 129, 135);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #d12f1b" class="">"</span><span style="font-variant-ligatures: no-common-ligatures;" class="">\</span><span style="font-variant-ligatures: no-common-ligatures; color: #d12f1b" class="">(</span><span style="font-variant-ligatures: no-common-ligatures" class="">floatNumber</span><span style="font-variant-ligatures: no-common-ligatures; color: #d12f1b" class="">)"</span><span style="font-variant-ligatures: no-common-ligatures;" class=""> </span><span style="font-variant-ligatures: no-common-ligatures; color: #008400" class="">// "1e+07"</span></div><div style="margin: 0px; line-height: normal; color: rgb(0, 132, 0);" class=""><span style="font-variant-ligatures: no-common-ligatures; color: #d12f1b" class="">"</span><span style="font-variant-ligatures: no-common-ligatures;" class="">\</span><span style="font-variant-ligatures: no-common-ligatures; color: #d12f1b" class="">(</span><span style="font-variant-ligatures: no-common-ligatures; color: #4f8187" class="">doubleNumer</span><span style="font-variant-ligatures: no-common-ligatures; color: #d12f1b" class="">)"</span><span style="font-variant-ligatures: no-common-ligatures;" class=""> </span><span style="font-variant-ligatures: no-common-ligatures" class="">// "10000000"</span></div></div></div><div style="margin: 0px; line-height: normal;" class=""><span style="font-variant-ligatures: no-common-ligatures;" class=""><br class=""></span></div><div style="margin: 0px; line-height: normal;" class=""><span style="font-variant-ligatures: no-common-ligatures;" class="">Is this expected behaviour?</span></div></div></div></div></div></blockquote><br class=""></div><div>cc'ing Tony and Philippe, who might be able to comment on the intended behavior of NSNumber here. When you cast using `as`, Swift will do the conversion through its Objective-C bridge, and will attempt to use a custom subclass of NSNumber that remembers the exact Swift type it was bridged as, such as Float or Double. There's a small chance your library is making assumptions that it's working with one of the standard NSNumber subclasses used by the Foundation implementation. If you call the NSNumber initializer `NSNumber(value: floatNumber)` instead of using the `as` conversion, you'll get one of these standard NSNumbers instead of a Swift-bridged NSNumber. Try that and see if it works. If using the initializer does indeed fix the problem, we'd appreciate a bug report, so we can investigate fixing the incompatibility with our NSNumber subclasses.</div><div><br class=""></div><div>-Joe</div></body></html>