适用于iPhone OS应用程序的可用内存

有一个函数或常量定义在iPhone OS中的应用程序的可用内存量？

我正在寻找一种独立于设备的方式（iPod touch，iPhone，iPad）来了解应用程序剩下多less内存。

Answer 1

这个函数将以字节的forms返回可用内存：

#import <mach/mach.h> #import <mach/mach_host.h> natural_t freeMemory(void) { mach_port_t host_port = mach_host_self(); mach_msg_type_number_t host_size = sizeof(vm_statistics_data_t) / sizeof(integer_t); vm_size_t pagesize; vm_statistics_data_t vm_stat; host_page_size(host_port, &pagesize); if (host_statistics(host_port, HOST_VM_INFO, (host_info_t)&vm_stat, &host_size) != KERN_SUCCESS) NSLog(@"Failed to fetch vm statistics"); natural_t mem_used = (vm_stat.active_count + vm_stat.inactive_count + vm_stat.wire_count) * pagesize; natural_t mem_free = vm_stat.free_count * pagesize; natural_t mem_total = mem_used + mem_free; return mem_free; } 

Answer 2

没有定义iPhone应用程序可以使用的最大内存量。 无论您的应用程序是否因内存不足而终止，取决于操作系统正在使用的任何algorithm，以及同时使用内存的其他应用程序（Safari，邮件等）。

Answer 3

下面的swift函数将返回系统空闲内存（ram）的字节数。 它会在失败时返回零。

 func systemFreeMemorySize() -> UInt? { let HOST_VM_INFO_COUNT: mach_msg_type_number_t = mach_msg_type_number_t(sizeof(vm_statistics_data_t) / sizeof(integer_t)) 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(&stats) { 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) }