SmartPhone Dev/iPhone
[xcode] iOS iphone memory check
랜썸
2010. 9. 30. 11:35
The iPhone has limited memory, and even simple applications can easily trigger a low memory warning. If you've implemented caching for performance reasons, you'll often find yourself balancing memory consumption against user experience.
Measuring the current available RAM allows one to make pre-emptive decisions about memory utilization before a low memory warning is triggered, possibly avoiding overly broad cache evictions when a memory warning is triggered.
I've seen this question come up a number of times, so here's a brief code snippet demonstrating how to determine available memory from the Mach VM statistics.
#import <mach/mach.h>
#import <mach/mach_host.h>
static void print_free_memory () {
mach_port_t host_port;
mach_msg_type_number_t host_size;
vm_size_t pagesize;
host_port = mach_host_self();
host_size = sizeof(vm_statistics_data_t) / sizeof(integer_t);
host_page_size(host_port, &pagesize);
vm_statistics_data_t vm_stat;
if (host_statistics(host_port, HOST_VM_INFO, (host_info_t)&vm_stat, &host_size) != KERN_SUCCESS)
NSLog(@"Failed to fetch vm statistics");
/* Stats in bytes */
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;
NSLog(@"used: %u free: %u total: %u", mem_used, mem_free, mem_total);
}
함수를 호출하면 호출할 당시의 사용된메모리 남은메모리 총메모리가 출력됩니다
(단위:바이트)
이를 응용해서 어플 실행하자마자 메모리와 리소스 로드후 메모리를 비교하면 현 어플의 실 사용 메모리도 알수 있습니다.
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