CFDictionaryGetValue 抛出 EXC_BAD_ACCESS

Question

我在 Objective-C 中找到了从 Getting graphic card information in objective C 截取的代码，我目前正在尝试将其转换为 Swift。我正在尝试从 CFMutableDictionary 中读取一个值（代码如下）。但是，当我调用函数 CFDictionaryGetValue 时，出现错误： "Thread 1: EXC_BAD_ACCESS (code=1, address=0x656d614e4f60)"

这是我当前的代码：

static func getGpuName() {
        var iterator: io_iterator_t = 0
        let errCode: kern_return_t  = IOServiceGetMatchingServices(kIOMasterPortDefault, IOServiceMatching("IOPCIDevice"), &iterator)
        if errCode != kIOReturnSuccess {
            fatalError("Could not retrieve the service dictionary of \"IOPCIDevice\"")
        }

        // iterate over the pci devices
        var device = IOIteratorNext(iterator)
        while device != 0 {
            var unmanagedServiceDictionary: Unmanaged<CFMutableDictionary>?
            if IORegistryEntryCreateCFProperties(device, &unmanagedServiceDictionary, kCFAllocatorDefault, 0) != kIOReturnSuccess {
                IOObjectRelease(device)
                continue
            }

            if let serviceDictionary: CFMutableDictionary = unmanagedServiceDictionary?.takeRetainedValue() {
                let name = CFDictionaryGetValue(serviceDictionary, "IOName")
            }

            // release the device
            IOObjectRelease(device)

            // get the next device from the iterator
            device = IOIteratorNext(iterator)
        }
}

有人知道我如何读取 CFMutableDictionary 的值吗？

谢谢:)

Answer 1

好的，经过更多研究后，我仍然不知道为什么会抛出错误。但是我通过将字典转换为 NSDictionary.

找到了解决方法

以下代码现在有效：

let serviceDictionary: NSDictionary = (unmanagedServiceDictionary?.takeRetainedValue())! as NSDictionary
if let name = serviceDictionary.value(forKey: "IOName") as? String {
    print(name)
}

Answer 2

处理 CoreFoundation API 真的很痛苦。

发生错误是因为您不能将文字 String 作为 CFDictionaryGetValue 的第二个参数传递，它必须是 UnsafeRawPointer.

但是解决方案非常简单。将字典转换为 Swift 字典

if let serviceDictionary = unmanagedServiceDictionary?.takeRetainedValue() as? [String:Any] {
    if let name = serviceDictionary["IOName"] as? String {
        print(name)
    }
}

CFDictionaryGetValue 抛出 EXC_BAD_ACCESS

CFDictionaryGetValue throws EXC_BAD_ACCESS

objective-c

swift

macos

core-foundation