我试图将ObjC stackoverflow答案转换为Swift并失败.看起来我正在通过一个UnsafeMutablePointer<mach_msg_type_number_t>我应该通过的时候inout mach_msg_type_number_t,我似乎无法解决我的问题.根据我对Swift指针文档的理解(不多),这些应该是可以互换的.
更多信息如下.
这是目标C:
struct task_basic_info info;
mach_msg_type_number_t size = sizeof(info);
kern_return_t kerr = task_info(mach_task_self(), TASK_BASIC_INFO, (task_info_t)&info, &size);
就我在Swift中所获得的而言(许多行更容易进行类型检查)
let name: task_name_t = mach_task_self_
let flavor: task_flavor_t = task_flavor_t(MACH_TASK_BASIC_INFO)
var info: mach_task_basic_info
var size: mach_msg_type_number_t = UnsignedFixed(sizeof(mach_task_basic_info_t))
let kerr = task_info(name, flavor, info as task_info_t, &size)
该task_info签名是:
func task_info(target_task: task_name_t, flavor: task_flavor_t, task_info_out: task_info_t, task_info_outCnt: UnsafeMutablePointer<mach_msg_type_number_t>) -> kern_return_t
并且最后一行的错误是:
Cannot convert the expression's type '(@!lvalue task_name_t, task_flavor_t, task_info_t, inout mach_msg_type_number_t)' to type 'kern_return_t'
Jer*_*rry 31
我有点更新了Airspeed Velocity对最新swift语法(Swift 3,beta 6)的回答,但这是我得到的:
func report_memory() {
var info = mach_task_basic_info()
let MACH_TASK_BASIC_INFO_COUNT = MemoryLayout<mach_task_basic_info>.stride/MemoryLayout<natural_t>.stride
var count = mach_msg_type_number_t(MACH_TASK_BASIC_INFO_COUNT)
let kerr: kern_return_t = withUnsafeMutablePointer(to: &info) {
$0.withMemoryRebound(to: integer_t.self, capacity: MACH_TASK_BASIC_INFO_COUNT) {
task_info(mach_task_self_,
task_flavor_t(MACH_TASK_BASIC_INFO),
$0,
&count)
}
}
if kerr == KERN_SUCCESS {
print("Memory in use (in bytes): \(info.resident_size)")
}
else {
print("Error with task_info(): " +
(String(cString: mach_error_string(kerr), encoding: String.Encoding.ascii) ?? "unknown error"))
}
}
希望这很有帮助.
Nat*_*ook 12
与C函数交互时,您不能依赖编译器的错误消息 - 按参数分解参数,按住命令单击,直到您知道正在使用的内容为止.首先,您遇到的类型是:
task_name_t: UInt32task_flavor_t: UInt32task_info_t: UnsafeMutablePointer<Int32>UnsafeMutablePointer<mach_msg_type_number_t>: UnsafeMutablePointer<UInt32>kern_return_t - Int32有一个棘手的Swift位以及你的代码中存在的错误.首先,task_info_out参数需要是a UnsafeMutablePointer<UInt32>,但实际上需要指向一个实例mach_task_basic_info.我们可以通过在调用时创建一个UnsafeMutablePointer<mach_task_basic_info>并将其包装在另一个 UnsafeMutablePointer中来解决这个问题- 编译器将使用类型推断来知道我们希望包装指针被子类型化为UInt32.
其次,当你应该调用时,你正在调用sizeof(mach_task_basic_info_t)(指向mach_task_basic_info)sizeinfo(mach_task_basic_info),因此你的字节数太低而无法容纳数据结构.
在进一步的研究中,这有点复杂.原始代码不正确,size应该初始化为常量MACH_TASK_BASIC_INFO_COUNT.不幸的是,这是一个宏,而不是一个简单的常量:
#define MACH_TASK_BASIC_INFO_COUNT (sizeof(mach_task_basic_info_data_t) / sizeof(natural_t))
Swift不会导入它们,所以我们需要自己重新定义它们.这是所有这些的工作代码:
// constant
let MACH_TASK_BASIC_INFO_COUNT = (sizeof(mach_task_basic_info_data_t) / sizeof(natural_t))
// prepare parameters
let name = mach_task_self_
let flavor = task_flavor_t(MACH_TASK_BASIC_INFO)
var size = mach_msg_type_number_t(MACH_TASK_BASIC_INFO_COUNT)
// allocate pointer to mach_task_basic_info
var infoPointer = UnsafeMutablePointer<mach_task_basic_info>.alloc(1)
// call task_info - note extra UnsafeMutablePointer(...) call
let kerr = task_info(name, flavor, UnsafeMutablePointer(infoPointer), &size)
// get mach_task_basic_info struct out of pointer
let info = infoPointer.move()
// deallocate pointer
infoPointer.dealloc(1)
// check return value for success / failure
if kerr == KERN_SUCCESS {
println("Memory in use (in bytes): \(info.resident_size)")
} else {
let errorString = String(CString: mach_error_string(kerr), encoding: NSASCIIStringEncoding)
println(errorString ?? "Error: couldn't parse error string")
}
Nate的答案非常好,但您可以通过调整来简化它.
首先,task_basic_info您可以在堆栈上创建结构,而不是分配/取消分配指针,然后使用withUnsafeMutablePointer直接获取指针,您可以传入该指针.
func report_memory() {
var info = mach_task_basic_info()
var count = mach_msg_type_number_t(sizeofValue(info))/4
let kerr: kern_return_t = withUnsafeMutablePointer(&info) {
task_info(mach_task_self_,
task_flavor_t(MACH_TASK_BASIC_INFO),
task_info_t($0),
&count)
}
if kerr == KERN_SUCCESS {
println("Memory in use (in bytes): \(info.resident_size)")
}
else {
println("Error with task_info(): " +
(String.fromCString(mach_error_string(kerr)) ?? "unknown error"))
}
}
Swift 5 + 组合，连续内存监控
像 XCODE 一样以 MB 为单位显示确切的内存
import Foundation
import Combine
enum MemoryMonitorState {
case started
case paused
}
class MemoryUsageCustom {
private var displayLink: CADisplayLink!
var state = MemoryMonitorState.paused
let subject = PassthroughSubject<String, Never>()
private static var sharedInstance: MemoryUsageCustom!
public class func shared() -> MemoryUsageCustom {
if self.sharedInstance == nil {
self.sharedInstance = MemoryUsageCustom()
}
return self.sharedInstance
}
private init() {
self.configureDisplayLink()
}
func startMemoryMonitor() {
if self.state == .started {
return
}
self.state = .started
self.start()
}
func stopMemoryMonitor() {
self.state = .paused
self.pause()
}
//--------------------------------------------------------------------------------
//MARK:- Display Link
//--------------------------------------------------------------------------------
func configureDisplayLink() {
self.displayLink = CADisplayLink(target: self, selector: #selector(displayLinkAction(displayLink:)))
self.displayLink.isPaused = true
self.displayLink?.add(to: .current, forMode: .common)
}
private func start() {
self.displayLink?.isPaused = false
}
/// Pauses performance monitoring.
private func pause() {
self.displayLink?.isPaused = true
}
@objc func displayLinkAction(displayLink: CADisplayLink) {
let memoryUsage = self.memoryUsage()
let bytesInMegabyte = 1024.0 * 1024.0
let usedMemory = Double(memoryUsage.used) / bytesInMegabyte
let totalMemory = Double(memoryUsage.total) / bytesInMegabyte
let memory = String(format: "%.1f of %.0f MB used", usedMemory, totalMemory)
// self.memoryString = memory
subject.send(memory)
}
func memoryUsage() -> (used: UInt64, total: UInt64) {
var taskInfo = task_vm_info_data_t()
var count = mach_msg_type_number_t(MemoryLayout<task_vm_info>.size) / 4
let result: kern_return_t = withUnsafeMutablePointer(to: &taskInfo) {
$0.withMemoryRebound(to: integer_t.self, capacity: 1) {
task_info(mach_task_self_, task_flavor_t(TASK_VM_INFO), $0, &count)
}
}
var used: UInt64 = 0
if result == KERN_SUCCESS {
used = UInt64(taskInfo.phys_footprint)
}
let total = ProcessInfo.processInfo.physicalMemory
return (used, total)
}
}
如何使用
//Start Monitoring
MemoryUsageCustom.shared().startMemoryMonitor()
var storage = Set<AnyCancellable>()
MemoryUsageCustom.shared().subject.sink {[weak self] (string) in
print(string)
}.store(in: &storage)
小智 5
Airspeed Velocity 在 Swift 3 中的答案...
func GetMemory()
{
var info = mach_task_basic_info()
var count = mach_msg_type_number_t(MemoryLayout.size(ofValue: info))/4
let kerr: kern_return_t = withUnsafeMutablePointer(to: &info)
{
task_info(mach_task_self_,
task_flavor_t(MACH_TASK_BASIC_INFO),
$0.withMemoryRebound(to: Int32.self, capacity: 1) { zeroPtr in
task_info_t(zeroPtr)
},
&count)
}
if kerr == KERN_SUCCESS {
print("Memory in use (in bytes): \(info.resident_size)")
}
else {
print("Error with task_info(): " +
(String.init(validatingUTF8: mach_error_string(kerr)) ?? "unknown error"))
}
}
要在 Swift 5 中快速复制和粘贴解决方案，请使用
func reportMemory() {
var taskInfo = task_vm_info_data_t()
var count = mach_msg_type_number_t(MemoryLayout<task_vm_info>.size) / 4
let result: kern_return_t = withUnsafeMutablePointer(to: &taskInfo) {
$0.withMemoryRebound(to: integer_t.self, capacity: 1) {
task_info(mach_task_self_, task_flavor_t(TASK_VM_INFO), $0, &count)
}
}
let usedMb = Float(taskInfo.phys_footprint) / 1048576.0
let totalMb = Float(ProcessInfo.processInfo.physicalMemory) / 1048576.0
result != KERN_SUCCESS ? print("Memory used: ? of \(totalMb)") : print("Memory used: \(usedMb) of \(totalMb)")
}
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