Question

'JSContext'没有下标成员，oc可以，但是迅速无法使用

我尝试过快速4

OC可以，例如

JSContext *context = [[JSContext alloc] init];
context[@"makeNSColor"] = ^(NSDictionary *rgb)
{float r = rgb[@"red"].floatValue;
float g = rgb[@"green"].floatValue;
float b = rgb[@"blue"].floatValue;
return [NSColor colorWithRed:(r / 255.f) green:(g / 255.f) blue:(b / 255.f) alpha:1.0];
};

Swift is Error：

var context = JSContext() as? JSContext     //Cannot assign value of type 'Any?' to type 'JSContext?'

        context!["makeNSColor"] = { rgb in     //Type 'JSContext' has no subscript member

            var r: Float = rgb?["red"].floatValue

            var g: Float = rgb?["green"].floatValue

            var b: Float = rgb?["blue"].floatValue

            return NSColor(red: CGFloat((r / 255.0)), green: CGFloat((g / 255.0)), blue: CGFloat((b / 255.0)), alpha: 1.0)

        }

它有两个错误：无法分配'Any？'类型的值。键入“ JSContext？”，类型“ JSContext”没有下标成员，我不知道如何解决它，您能告诉我如何解决它，非常感谢。

我试图更改上下文！如！ NSMutableDictionary或[String，Any]，但仍然错误，无法更改

Answer 1

将以下内容用于等效操作

let colorHandle: @convention(block) ([String : Any]) -> UIColor = { rgb in
    let r = rgb["red"] as! CGFloat
    let g = rgb["green"] as! CGFloat
    let b = rgb["blue"] as! CGFloat

    return UIColor(red: r / 255.0, green: g / 255.0, blue: b / 255.0, alpha: 1.0)
}

context?.setObject(colorHandle, forKeyedSubscript: "makeNSColor" as NSCopying & NSObjectProtocol)

Answer 2

我不知道什么是对象makeNSColor。但是，如果它是var makeNSColor = {red : 10/255, green : 10/255, blue : 255/255, a : 1};，这是一个很好的示例，说明如何从字典makeNSColor创建UIColor：

    func f () {
        let context = JSContext()!
        let script = """
var makeNSColor = {red : 10/255, green : 10/255, blue : 255/255, a : 1};
"""
        let cc = context.evaluateScript(script).context // result is
        let val = cc?.objectForKeyedSubscript("makeNSColor")
        guard let dict = val?.toDictionary() as? [String : CGFloat] else {return}
        let color = UIColor(displayP3Red: dict["red"] ?? 0, green: dict["green"] ?? 0, blue: dict["blue"] ?? 0, alpha: dict["a"] ?? 0)

        print(color)
    }

如果要在JS中将makeNSColor创建为Dictionary，请使用下一个函数：

    func addColor (r : Float, g : Float, b : Float) {
        let context = JSContext()!
        let script = """
var makeNSColor = {red : \(r)/255, green : \(g)/255, blue : \(b)/255, a : 1};
"""
        let cc = context.evaluateScript(script).context // result is

        // next code only needed to check the `makeNSColor`
        let val = cc?.objectForKeyedSubscript("makeNSColor")
        guard let dict = val?.toDictionary() as? [String : CGFloat] else {return}
        let color = UIColor(displayP3Red: dict["red"] ?? 0, green: dict["green"] ?? 0, blue: dict["blue"] ?? 0, alpha: dict["a"] ?? 0)

        print(color)
    }

如何将OC JSContext [@“ makeNSColor”]更改为快速

2 个答案: