x/mobile: handle assets on iOS

[CanRui-Wu]

What version of Go are you using (go version)?

$ go version
go version go1.12.7 darwin/amd64

Does this issue reproduce with the latest release?

Yes

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/wucanrui/Library/Caches/go-build"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/wucanrui/go"
GOPROXY=""
GORACE=""
GOROOT="/usr/local/Cellar/go/1.12.7/libexec"
GOTMPDIR=""
GOTOOLDIR="/usr/local/Cellar/go/1.12.7/libexec/pkg/tool/darwin_amd64"
GCCGO="gccgo"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/0_/j6m36l9s0psg9xm5ggt2_b680000gp/T/go-build792194215=/tmp/go-build -gno-record-gcc-switches -fno-common"

What did you do?

I am new to IOS.

I build an IOS framework file by using gomobile.

I run gomobile bind -target=ios xxx (xxx is a package with a subdirectory "assets", and there are a file 'config.json' in assets).

In xxx package, I use asset.Open() to get the asset but it failed with log (no such file or directory). And then when I check the 'bind_iosapp.go' in gomobile, I find that it does not handle the "assets" directory at all.

What did you expect to see?

I can use my asset file in xxx.framework by using golang.

What did you see instead?

I see this tip on godoc of gomobile.(On iOS an asset is a resource stored in the application bundle. Resources can be loaded using the same relative paths). How can I get the asset file? Should I use the asset.Open API? What the path I should put the asset file into IOS is?

[julieqiu]

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