iOS 获取内存大小使用情况（进度条显示）

//返回存储内存占用比例
- (NSString *)getFreeDiskspaceRate{

    float totalSpace;
    float totalFreeSpace=0.f;
    
    NSError *error = nil;
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSDictionary *dictionary = [[NSFileManager defaultManager] attributesOfFileSystemForPath:[paths lastObject] error: &error];
    if (dictionary) {
        NSNumber *fileSystemSizeInBytes = [dictionary objectForKey: NSFileSystemSize];
        NSNumber *freeFileSystemSizeInBytes = [dictionary objectForKey:NSFileSystemFreeSize];
        totalSpace = [fileSystemSizeInBytes floatValue]/1024.0f/1024.0f/1024.0f;
        totalFreeSpace = [freeFileSystemSizeInBytes floatValue]/1024.0f/1024.0f/1024.0f;

        //totalString、freeString是定义两个全局变量 进度条上显示大小数据用
        totalString = [self getFileSizeString:[fileSystemSizeInBytes floatValue]];
        freeString = [self getFileSizeString:[freeFileSystemSizeInBytes floatValue]];
        NSLog(@"打印totalString：%@,freeString:%@",totalString,freeString);
      
        NSLog(@"Memory Capacity of %.2f GB with %.2f GB Free memory available.", totalSpace, totalFreeSpace);
        
    } else {
        NSLog(@"Error Obtaining System Memory Info: Domain = %@, Code = %@", [error domain], [error code]);

    }
    NSString *freeStr = [NSString stringWithFormat:@"%.3f",(totalSpace-totalFreeSpace)/totalSpace];//进度条比例
    return freeStr;
}

NSFileManager *fm = [NSFileManager defaultManager];
    NSDictionary *fat = [fm attributesOfFileSystemForPath:NSHomeDirectory() error:nil];
    NSLog(@"容量：%lldG 可用容量：%lldG",[[fat objectForKey:NSFileSystemSize]longLongValue]/1000000000,[[fat objectForKey:NSFileSystemFreeSize]longLongValue]/1000000000);
    struct statfs buf;
    long long freespace = -1;
    if(statfs("/var", &buf) >= 0){
        freespace = (long long)(buf.f_bsize * buf.f_bfree);
    }
    NSLog(@"%@",[NSString stringWithFormat:@"手机剩余存储空间为：%qi GB" ,freespace/1024/1024/1024]);

-(NSString *)getFileSizeString:(CGFloat)size
{
    if (size>1024*1024*1024){
        return [NSString stringWithFormat:@"%.1fG",size/1024/1024/1024];//大于1G，则转化成G单位的字符串
    }
    else if(size<1024*1024*1024&&size>=1024*1024)//大于1M，则转化成M单位的字符串
    {
        return [NSString stringWithFormat:@"%.1fM",size/1024/1024];
    }
    else if(size>=1024&&size<1024*1024) //不到1M,但是超过了1KB，则转化成KB单位
    {
        return [NSString stringWithFormat:@"%.1fK",size/1024];
    }
    else//剩下的都是小于1K的，则转化成B单位
    {
        return [NSString stringWithFormat:@"%.1fB",size];
    }
}