set an floating number to Float sometime fail.

[coder-free]

import Runtime

class A {
    var value1: Float?
    var value2: Double?
}

func test() {
    let json = "{\"beans\":[{\"value1\":1.2,\"value2\":1.3},{\"value1\":2.2,\"value2\":2.3}]}"
    if let data = json.data(using: .utf8) {
        if let obj = try? JSONSerialization.jsonObject(with: data) {
            let dictionary: Dictionary<String, Any> = obj as! Dictionary<String, Any>
            if let beans = dictionary["beans"] as? Array<Dictionary<String, Any>> {
                for beanDic in beans {
                    print("=========================================")
                    var bean = A()
                    if let info = try? typeInfo(of: type(of: bean)) {
                        let properties = info.properties()
                        for (key, value) in beanDic {
                            if properties.contains(key) {
                                if let property = try? info.property(named: key) {
                                    print("set \(value)[type:\(type(of: value))] -> \(key)[type:\(property.type)]")
                                    try? property.set(value: value, on: &bean)
                                }
                            }
                        }
                    }
                    print("-----------------------------------------")
                    print("\(type(of: bean.value1)):\(String(describing: bean.value1)), \(type(of: bean.value2)):\(String(describing: bean.value2))")
                    print("=========================================")
                }
            }
        }
    }
}

extension TypeInfo {
    func properties() -> [String] {
        var properties: [String] = []
        for property in self.properties {
            properties.append(property.name)
        }
        return properties
    }
}

test()

got log:

=========================================
set 1.2[type:__NSCFNumber] -> value1[type:Optional<Float>]
set 1.3[type:__NSCFNumber] -> value2[type:Optional<Double>]
-----------------------------------------
Optional<Float>:nil, Optional<Double>:Optional(1.3)
=========================================
=========================================
set 2.2[type:__NSCFNumber] -> value1[type:Optional<Float>]
set 2.3[type:__NSCFNumber] -> value2[type:Optional<Double>]
-----------------------------------------
Optional<Float>:nil, Optional<Double>:Optional(2.3)
=========================================

Set Floating value to Double success. Set Floating value to Float fail.

[wickwirew]

Its because the values actual type from JSONSerialization.jsonObject is a Double, not a Float. Runtime will not auto convert any type for. You would need to convert it manually before setting it:

if let property = try? info.property(named: key) {
    if value is Double {
        try? property.set(value: Float(value), on: &bean)
    } else {
        try? property.set(value: value, on: &bean)
    }
}

[coder-free]

@wickwirew ok, thank you