Question

在Swift 2.2中，我可以使用unsafeAddressOf将VENDOR和PRODUCT ID添加到usb匹配字典中。

var serviceMatchingDictionary = IOServiceMatching(kIOUSBDeviceClassName)

private let VendorID = 0x8564
private let ProductID = 0x5000

let vendorIDString = kUSBVendorID as CFStringRef!
let productIDString = kUSBProductID as CFStringRef!


CFDictionarySetValue(serviceMatchingDictionary, unsafeAddressOf(vendorIDString), unsafeAddressOf(VendorID))
CFDictionarySetValue(serviceMatchingDictionary, unsafeAddressOf(productIDString), unsafeAddressOf(ProductID))

在Swift 3中，我使用withUnsafePointer(to arg: inout T, _ body: (UnsafePointer) throws -> Result) rethrows -> Result。

然而，它没有用。它可以打印出地址，但在调用CFDictionarySetValue

时会崩溃

withUnsafePointer(to: &VendorID) { vendorIDPtr in
        withUnsafePointer(to: &ProductID, { productIDPtr in
            withUnsafePointer(to: &vendorIDString, { vendorIDStringPtr in
                withUnsafePointer(to: &productIDString, { productIDStringPtr in
                    // Thread1: EXC_BAD_ACCESS(code=1, address=0x0)
                    CFDictionarySetValue(matchingDict, vendorIDStringPtr, vendorIDPtr)
                    CFDictionarySetValue(matchingDict, productIDStringPtr, productIDPtr)
                })
            })
        })
    }

Answer 1

您尝试过的崩溃发生Swift 3代码是因为整数变量的地址被传递给一个需要Foundation 对象地址的函数。但是你可以完全避免使用CFDictionarySetValue和不安全指针操作此任务。

IOServiceMatching()会返回免费的CFMutableDictionary 桥接到NSMutableDictionary：

let matchingDictionary: NSMutableDictionary = IOServiceMatching(kIOUSBDeviceClassName)

现在您只需将ID添加为NSNumber个对象：

let vendorID = 0x8564
let productID = 0x5000

matchingDictionary[kUSBVendorID] = vendorID as NSNumber
matchingDictionary[kUSBProductID] = productID as NSNumber

如何将供应商/产品ID添加到USB匹配字典

1 个答案: