The short code below is useful when building a log system for your iOS application with Swift. It displays exactly the percentage of usage on each CPU core of the iOS device.
The function returns the value of CPU usage:
func getCPULoadInfo()-> String{
var cpuUsageInfo = ""
var cpuInfo: processor_info_array_t!
var prevCpuInfo: processor_info_array_t?
var numCpuInfo: mach_msg_type_number_t = 0
var numPrevCpuInfo: mach_msg_type_number_t = 0
var numCPUs: uint = 0
let CPUUsageLock: NSLock = NSLock()
var usage:Float32 = 0
let mibKeys: [Int32] = [ CTL_HW, HW_NCPU ]
mibKeys.withUnsafeBufferPointer() { mib in
var sizeOfNumCPUs: size_t = MemoryLayout<uint>.size
let status = sysctl(processor_info_array_t(mutating: mib.baseAddress), 2, &numCPUs, &sizeOfNumCPUs, nil, 0)
if status != 0 {
numCPUs = 1
}
}
var numCPUsU: natural_t = 0
let err: kern_return_t = host_processor_info(mach_host_self(), PROCESSOR_CPU_LOAD_INFO, &numCPUsU, &cpuInfo, &numCpuInfo);
if err == KERN_SUCCESS {
CPUUsageLock.lock()
for i in 0 ..< Int32(numCPUs) {
var inUse: Int32
var total: Int32
if let prevCpuInfo = prevCpuInfo {
inUse = cpuInfo[Int(CPU_STATE_MAX * i + CPU_STATE_USER)]
- prevCpuInfo[Int(CPU_STATE_MAX * i + CPU_STATE_USER)]
+ cpuInfo[Int(CPU_STATE_MAX * i + CPU_STATE_SYSTEM)]
- prevCpuInfo[Int(CPU_STATE_MAX * i + CPU_STATE_SYSTEM)]
+ cpuInfo[Int(CPU_STATE_MAX * i + CPU_STATE_NICE)]
- prevCpuInfo[Int(CPU_STATE_MAX * i + CPU_STATE_NICE)]
total = inUse + (cpuInfo[Int(CPU_STATE_MAX * i + CPU_STATE_IDLE)]
- prevCpuInfo[Int(CPU_STATE_MAX * i + CPU_STATE_IDLE)])
} else {
inUse = cpuInfo[Int(CPU_STATE_MAX * i + CPU_STATE_USER)]
+ cpuInfo[Int(CPU_STATE_MAX * i + CPU_STATE_SYSTEM)]
+ cpuInfo[Int(CPU_STATE_MAX * i + CPU_STATE_NICE)]
total = inUse + cpuInfo[Int(CPU_STATE_MAX * i + CPU_STATE_IDLE)]
}
let coreInfo = Float(inUse) / Float(total)
usage += coreInfo
print(String(format: "Core: %u Usage: %f", i, Float(inUse) / Float(total)))
}
cpuUsageInfo = String(format:"%.2f",100 * Float(usage) / Float(numCPUs))
CPUUsageLock.unlock()
if let prevCpuInfo = prevCpuInfo {
let prevCpuInfoSize: size_t = MemoryLayout<integer_t>.stride * Int(numPrevCpuInfo)
vm_deallocate(mach_task_self_, vm_address_t(bitPattern: prevCpuInfo), vm_size_t(prevCpuInfoSize))
}
prevCpuInfo = cpuInfo
numPrevCpuInfo = numCpuInfo
cpuInfo = nil
numCpuInfo = 0
} else {
print("Error!")
}
return cpuUsageInfo
}
Test results on Xcode 10.1:
