如何修复Xcode 8.1中的这个错误（返回host_statistics）？我想知道设备

问题描述：

func systemFreeMemorySize() -> UInt? 
{ 
    let HOST_VM_INFO_COUNT: mach_msg_type_number_t = mach_msg_type_number_t(MemoryLayout<vm_statistics_data_t>.size/MemoryLayout<integer_t>.size) 

    let host: host_t = mach_host_self() 
    var pageSize: vm_size_t = vm_size_t() 
    let hostPageSizeKernStatus: kern_return_t = host_page_size(host, &pageSize) 
    /* 
    guard hostPageSizeKernStatus == KERN_SUCCESS else { 
     NSLog("Error with host_page_size(): " + (String.fromCString(mach_error_string(hostPageSizeKernStatus)) ?? "unknown error")) 
     return nil 
    }*/ 
    var stats: vm_statistics_data_t = vm_statistics_data_t() 
    var count: mach_msg_type_number_t = HOST_VM_INFO_COUNT 

    let kernStatus: kern_return_t = withUnsafeMutablePointer(to: &stats) { 
     // *** Error on following line: 
     return host_statistics(host, HOST_VM_INFO, host_info_t($0), &count) 
    } 

    /* 
    guard kernStatus == KERN_SUCCESS else { 
     NSLog("Error with host_statistics(): " + (String.fromCString(mach_error_string(kernStatus)) ?? "unknown error")) 
     return nil 
    } */ 

    return UInt(stats.free_count) * UInt(pageSize) 
}

的空闲内存在行回报host_statistics（主机，HOST_VM_INFO，host_info_t（$ 0），&计数）有一个错误：“初始化”不可用：使用“withMemoryRebound（以：容量：_）'暂时将内存视为另一种与布局兼容的类型。如何修复Xcode 8.1中的这个错误（返回host_statistics）？我想知道设备

如何解决这个问题？

答

for Swift 3.1。（我增加了一些更多的代码来检查所有信息，你可能需要的。）

func freeMemory()->UInt64 { 


    let host_port :mach_port_t = mach_host_self() 

    let HOST_BASIC_INFO_COUNT = MemoryLayout<host_basic_info>.stride/MemoryLayout<integer_t>.stride 
    var size = mach_msg_type_number_t(HOST_BASIC_INFO_COUNT) 
    var hostInfo = host_basic_info() 

    let status1 = withUnsafeMutablePointer(to: &hostInfo) { 
     $0.withMemoryRebound(to: integer_t.self, capacity: Int(size)) { 
      host_info(host_port, Int32(HOST_BASIC_INFO), $0, &size) 
     } 
    } 

    print(status1, hostInfo) 

    // THE FIX: 

    var pageSize: vm_size_t = vm_size_t() 
    let hostPageSizeKernStatus: kern_return_t = host_page_size(host_port, &pageSize) 


    var vm_stat = vm_statistics_data_t() 
    let HOST_VM_INFO_COUNT = MemoryLayout<vm_statistics_data_t>.stride/MemoryLayout<integer_t>.stride 
    var size2 = mach_msg_type_number_t(HOST_VM_INFO_COUNT) 

    let status2 = withUnsafeMutablePointer(to: &vm_stat) { 
     $0.withMemoryRebound(to: integer_t.self, capacity: Int(size2)) { 
      host_statistics(host_port, Int32(HOST_VM_INFO), $0, &size2) 
      //C: 
      // (void) host_statistics(host_port, HOST_VM_INFO, (host_info_t)&vm_stat, &host_size); 

     } 
    } 

    print(status2, vm_stat) 

    let freePages = UInt64(vm_stat.free_count) 
    let result = freePages * UInt64(pageSize) 


    return result 
}

啊，我的MacBook我得到：

47483648，cpu_type的：7，cpu_subtype：8，cpu_threadtype：1，physical_cpu：4， physical_cpu_max：4，logical_cpu：8，logical_cpu_max：8，max_mem的：17179869184）

vm_statistics（free_count：1240186，active_count：1765236，inactive_count：124649，wire_count：684265，zero_fill_count：921561165，重新激活：4645359，pageins：19628659， pageout：23555，错误：1940619345，cow_faults：94990152，查找：2563634，命中：40，purgeable_count：166562，清除：4217152，specu lative_count：306146）

并且结果是：5079801856 即5GB

如何修复Xcode 8.1中的这个错误（返回host_statistics）？我想知道设备

相关推荐