兩種方法均與嗶哩嗶哩剩餘記憶體統計比較過，資料一樣，且都小於iOS系統 <設定>裡統計的資料；

方法一：

#include <sys/param.h>
#include <sys/mount.h>

+ (NSString *)freeDiskSpaceInBytes{
    struct statfs buf;
    unsigned long long freeSpace = -1;
    if (statfs("/var", &buf) >= 0) {
        freeSpace = (unsigned long long
 
)(buf.f_bsize * buf.f_bavail);
    }
     NSString *str = [NSString stringWithFormat:@"手機剩餘儲存空間為：%0.2lld MB",freeSpace/1024/1024];
    return str;
}

方法二：

  /// 總大小
    float totalsize = 0.0;
    /// 剩餘大小
    float freesize = 0.0;
    /// 是否登入
    NSError *error = nil;
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES
 
);
    NSDictionary *dictionary = [[NSFileManager defaultManager] attributesOfFileSystemForPath:[paths lastObject] error: &error];
    if (dictionary)
    {
        NSNumber *_free = [dictionary objectForKey:NSFileSystemFreeSize];
        freesize = [_free unsignedLongLongValue]*1.0/(1024);

        NSNumber
 
 *_total = [dictionary objectForKey:NSFileSystemSize];
        totalsize = [_total unsignedLongLongValue]*1.0/(1024);
    } else
    {
        NSLog(@"Error Obtaining System Memory Info: Domain = %@, Code = %ld", [error domain], (long)[error code]);
    }
    NSLog(@"totalsize = %.2f, freesize = %f",totalsize/1024/1024/1024, freesize/1024);