How to determine the amount of memory allocated to an application during its operation?

In iOS, to determine the application's memory usage during its operation, you can use Xcode tools, such as Instruments with the Allocations template or Memory Graph Debugger. They show the amount of allocated memory, its size, and type.

You can also programmatically obtain information about current memory usage through APIs, for example, using task_info from the Mach API:

import MachO
import Darwin

func reportMemory() -> UInt64? {
    var info = task_basic_info()
    var count = mach_msg_type_number_t(MemoryLayout<task_basic_info>.size) / 4

    let kerr: kern_return_t = withUnsafeMutablePointer(to: &info) {
        $0.withMemoryRebound(to: integer_t.self, capacity: Int(count)) {
            task_info(mach_task_self_, task_flavor_t(TASK_BASIC_INFO), $0, &count)
        }
    }

    if kerr == KERN_SUCCESS {
        return UInt64(info.resident_size)
    } else {
        return nil
    }
}

if let memoryUsed = reportMemory() {
    print("Memory used: \(memoryUsed) bytes")
}

This code returns the amount of memory occupied (resident size) by the current application. However, for detailed analysis, it is better to use Xcode tools.