Member 'index' cannot be used on value of protocol type 'collection'; use a generic constraint instead

[malaypatel11]

if colorString.hasPrefix("#")
{
var argb: [UInt] = [255, 0, 0, 0]
let colorString = colorString.unicodeScalars
var length = colorString.count
var index = colorString.startIndex
let endIndex = colorString.endIndex

        **index = <#T##Collection corresponding to `index`##Collection#>.index(index, offsetBy: 1)**
        length = length - 1

        if length == 3 || length == 6 || length == 8
        {
            var i = length == 8 ? 0 : 1
            while index < endIndex
            {
                var c = colorString[index]
                **index = <#T##Collection corresponding to `index`##Collection#>.index(index, offsetBy: 1)**

                var val = (c.value >= 0x61 && c.value <= 0x66) ? (c.value - 0x61 + 10) : c.value - 0x30
                argb[i] = UInt(val) * 16
                if length == 3
                {
                    argb[i] = argb[i] + UInt(val)
                }
                else
                {
                    c = colorString[index]
                    **index = <#T##Collection corresponding to `index`##Collection#>.index(index, offsetBy: 1)**

                    val = (c.value >= 0x61 && c.value <= 0x66) ? (c.value - 0x61 + 10) : c.value - 0x30
                    argb[i] = argb[i] + UInt(val)
                }

                i += 1
            }
        }

[liuxuan30]

No idea why asked here. closing. Stack Overflow is a better place to ask this

[malaypatel11]

Because these error comes in your framework that's why I am asked here.

[liuxuan30]

I don't know what's the problem you are talking, either reproducing or where it crashes.
Need more details like how to reproduce or crash trace, not just pasting an error message and some code that we don't know where's the issue.

[malaypatel11]

http://pasteboard.co/1knihIRyg.png
can you see above image so you can better idea.

[danielgindi]

It seems like an error that should have been raised in compile time. Strange.

[danielgindi]

I see no crash there. And no complaint.
You are probably compiling with Xcode 7 or something like that.

[malaypatel11]

Yes thats compile and build failed. I am using Xcode 8 and swift 3.0.

[liuxuan30]

Please download the code again, I never saw code like yours on my side:

        if colorString.hasPrefix("#")
        {
            var argb: [UInt] = [255, 0, 0, 0]
            let colorString = colorString.unicodeScalars
            var length = colorString.count
            var index = colorString.startIndex
            let endIndex = colorString.endIndex

            index = colorString.index(after: index) <===== watch this line
            length = length - 1

            if length == 3 || length == 6 || length == 8