iOS NSFileManager管理目录路径（3）——文件大小

计算文件大小，既可以计算指定文件路径的某个文件大小，也可以计算指定目录的大小，该目录可能包含多个子目录及文件。

1、计算单个文件的大小dobule

+ (BOOL)isFileExists:(NSString *)filepath
{
    return [[NSFileManager defaultManager] fileExistsAtPath:filepath];
}

+ (NSDictionary *)fileAttributesWithFilePath:(NSString *)filePath
{
    if ([self isFileExists:filePath])
    {
        return [[NSFileManager defaultManager] attributesOfItemAtPath:filePath error:nil];
    }
    return nil;
}

+ (double)fileSizeNumberWithFilePath:(NSString *)filePath
{
    if ([self isFileExists:filePath])
    {
        return [[self fileAttributesWithFilePath:filePath] fileSize];
    }
    return 0.0;
}

2、文件大小转换成NSString

+ (NSString *)fileSizeStringConversionWithNumber:(double)fileSize
{
    NSString *message = nil;
    
    // 1MB = 1024KB 1KB = 1024B
    double size = fileSize;
    if (size > (1024 * 1024))
    {
        size = size / (1024 * 1024);
        message = [NSString stringWithFormat:@"%.2fM", size];
    }
    else if (size > 1024)
    {
        size = size / 1024;
        message = [NSString stringWithFormat:@"%.2fKB", size];
    }
    else if (size > 0.0)
    {
        message = [NSString stringWithFormat:@"%.2fB", size];
    }
    
    return message;
}

3、计算某个目录的大小

注意事项：统计过程中必须计算其所有层级子目录的相关文件大小，避免只统计当前子目录下的文件。

只统计到当前子目录时，是因为使用了不正确函数造成的，正确的统计方法如下所示。

// 错误的遍历方法
- (nullable NSArray<NSString *> *)contentsOfDirectoryAtPath:(NSString *)path error:(NSError **)error NS_AVAILABLE(10_5, 2_0)

// 正确的遍历方法
- (nullable NSArray<NSString *> *)subpathsAtPath:(NSString *)path;

// 正确的遍历方法
- (nullable NSDirectoryEnumerator<NSString *> *)enumeratorAtPath:(NSString *)path;

示例如下：

方法1

+ (double)fileSizeTotalNumberWithDirectory:(NSString *)directory
{
    __block double size = 0.0;
    if ([self isFileExists:directory])
    {        
        NSDirectoryEnumerator *dirEnum = [[NSFileManager defaultManager] enumeratorAtPath:directory];
        NSMutableArray *array = [[NSMutableArray alloc] init];
        NSString *path = nil;
        while (path = [dirEnum nextObject])
        {
            [array addObject:path];
        }
        
        [array enumerateObjectsUsingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
            NSString *filePath = [directory stringByAppendingPathComponent:obj];
            if ([self isFileDirectoryWithFilePath:filePath])
            {
                [self fileSizeTotalNumberWithDirectory:filePath];
            }
            size += [self fileSizeNumberWithFilePath:filePath];
        }];
    }
    return size;
}

方法2

+ (double)fileSizeTotalNumberWithDirectory:(NSString *)directory
{
    __block double size = 0.0;
    if ([self isFileExists:directory])
    {
        NSArray *array = [[NSFileManager defaultManager] subpathsAtPath:directory];
        
        [array enumerateObjectsUsingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
            NSString *filePath = [directory stringByAppendingPathComponent:obj];
            if ([self isFileDirectoryWithFilePath:filePath])
            {
                [self fileSizeTotalNumberWithDirectory:filePath];
            }
            size += [self fileSizeNumberWithFilePath:filePath];
        }];
    }
    return size;
}

方法3

#include <sys/stat.h>
#include <dirent.h>

+ (double)fileSizeTotalNumberWithDirectory:(NSString *)directory
{
    const char *folderPath = [directory cStringUsingEncoding:NSUTF8StringEncoding];
    return [self folderSizeAtPath:folderPath];
}

// 遍历目录（注意添加头文件 #include <sys/stat.h> #include <dirent.h>）
+ (long long)folderSizeAtPath:(const char *)folderPath
{
    long long folderSize = 0;
    DIR *dir = opendir(folderPath);
    if (dir == NULL)
    {
        return 0;
    }
    struct dirent *child;
    while ((child = readdir(dir)) != NULL)
    {
        if (child->d_type == DT_DIR && (
                                        (child->d_name[0] == '.' && child->d_name[1] == 0) || // 忽略目录 .
                                        (child->d_name[0] == '.' && child->d_name[1] == '.' && child->d_name[2] == 0) // 忽略目录 ..
                                        ))
        {
            continue;
        }
        
        int folderPathLength = strlen(folderPath);
        char childPath[1024]; // 子文件的路径地址
        stpcpy(childPath, folderPath);
        if (folderPath[folderPathLength-1] != '/')
        {
            childPath[folderPathLength] = '/';
            folderPathLength++;
        }
        stpcpy(childPath+folderPathLength, child->d_name);
        childPath[folderPathLength + child->d_namlen] = 0;
        if (child->d_type == DT_DIR)
        {
            // directory
            folderSize += [self folderSizeAtPath:childPath]; // 递归调用子目录
            // 把目录本身所占的空间也加上
            struct stat st;
            if (lstat(childPath, &st) == 0)
            {
                folderSize += st.st_size;
            }
        }
        else if (child->d_type == DT_REG || child->d_type == DT_LNK)
        {
            // file or link
            struct stat st;
            if (lstat(childPath, &st) == 0)
            {
                folderSize += st.st_size;
            }
        }
    }
    return folderSize;
}