NSData 数据对象
NSData : NSObject
初始化
- 准备数据
int len = 2;
Byte *bytes = malloc(sizeof(Byte) * len);
bytes[0] = 0x00;
bytes[1] = 0x0f;
// 栈
Byte bytes2[] = {0x01, 0x02};
- 初始化 1
NSData *data1 = [NSData data];
- 初始化 2
NSData *data2 = [NSData dataWithBytes:bytes length:2];// bytes free 后 不影响 data2
free(bytes1);
- 初始化 3
NSData *data3 = [NSData dataWithBytesNoCopy:bytes length:2];// bytes free 后 影响 data3
free(bytes1);
- 初始化 4
NSData *data4 = [NSData dataWithBytesNoCopy:bytes length:2 freeWhenDone:YES];// 可以接管 free
- 初始化 5
NSData *data5 = [NSData dataWithData:data1];
读取文件 data
- 准备本地文件
NSString *filePath = [[NSBundle mainBundle] pathForResource:@"test" ofType:@"pdf"];
- 无参数模式
NSData *data = [NSData dataWithContentsOfFile:filePath];
NSData *data2 = [NSData dataWithContentsOfURL:[NSURL fileURLWithPath:filePath]];
- 参数模式
NSError *error;
NSData *data3 = [NSData dataWithContentsOfFile:filePath options:NSDataReadingMappedIfSafe error:&error];
NSData *data4 = [NSData dataWithContentsOfURL:[NSURL fileURLWithPath:filePath] options:NSDataReadingMappedIfSafe error:&error];
// typedef NS_OPTIONS(NSUInteger, NSDataReadingOptions) {
// NSDataReadingMappedIfSafe = 1UL << 0, // 安全的情况下，使用文件映射（不加入内存）
// NSDataReadingUncached = 1UL << 1, // 加入内存
// NSDataReadingMappedAlways = 1UL << 3, // 总是不加入内存
// };
写入文件
- 准备文件 data
UIImage *image = [UIImage imageNamed:@"image"];
NSData *imageData = UIImagePNGRepresentation(image);
NSString *filePath = [NSString stringWithFormat:@"%@/image.png",NSHomeDirectory()];
NSURL *fileUrl = [NSURL fileURLWithPath:filePath];
- 一般
BOOL res1 = [imageData writeToFile:filePath atomically:NO];
BOOL res2 = [imageData writeToURL:fileUrl atomically:YES];
- 复杂
NSError *error;
BOOL res3 = [imageData writeToFile:filePath options:NSDataWritingAtomic error:&error];
BOOL res4 = [imageData writeToURL:fileUrl options:NSDataWritingWithoutOverwriting error:&error];
// typedef NS_OPTIONS(NSUInteger, NSDataWritingOptions) {
// NSDataWritingAtomic = 1UL << 0, // 覆盖
// NSDataWritingWithoutOverwriting = 1UL << 1, // 不覆盖，已存在时，返回 NO
// NSDataWritingFileProtectionNone = 0x10000000, // 以下都是 文件保护 相关
// NSDataWritingFileProtectionComplete = 0x20000000,
// NSDataWritingFileProtectionCompleteUnlessOpen = 0x30000000,
// NSDataWritingFileProtectionCompleteUntilFirstUserAuthentication = 0x40000000,
// NSDataWritingFileProtectionMask = 0xf0000000,
// };
Base64 处理
- 准备 data
Byte bytes[] = {
0x01, 0x02, 0x03, 0x04, 0x01, 0x02, 0x03, 0x04,
0x01, 0x02, 0x03, 0x04, 0x01, 0x02, 0x03, 0x04,
0x01, 0x02, 0x03, 0x04, 0x01, 0x02, 0x03, 0x04,
0x01, 0x02, 0x03, 0x04, 0x01, 0x02, 0x03, 0x04,
0x01, 0x02, 0x03, 0x04, 0x01, 0x02, 0x03, 0x04,
0x01, 0x02, 0x03, 0x04, 0x01, 0x02, 0x03, 0x04,
0x01, 0x02, 0x03, 0x04, 0x01, 0x02, 0x03, 0x04,
0x01, 0x02, 0x03, 0x04, 0x01, 0x02, 0x03, 0x04,
0x01, 0x02, 0x03, 0x04, 0x01, 0x02, 0x03, 0x04,
0x01, 0x02, 0x03, 0x04, 0x01, 0x02, 0x03, 0x04,
0x01, 0x02, 0x03, 0x04, 0x01, 0x02, 0x03, 0x04,
0x01, 0x02, 0x03, 0x04, 0x01, 0x02, 0x03, 0x04
};
NSData *data = [NSData dataWithBytes:bytes length:96];
- data <-> base64String
NSString *base64String1 = [data base64EncodedStringWithOptions:NSDataBase64Encoding64CharacterLineLength];
// typedef NS_OPTIONS(NSUInteger, NSDataBase64EncodingOptions) {
// 2 选 1，64\76 长度分割
// NSDataBase64Encoding64CharacterLineLength = 1UL << 0,
// NSDataBase64Encoding76CharacterLineLength = 1UL << 1,
//
// 下面 2 个参数，默认都有，也就是默认添加 \r\n
// NSDataBase64EncodingEndLineWithCarriageReturn = 1UL << 4, // 添加 \r
// NSDataBase64EncodingEndLineWithLineFeed = 1UL << 5,// 添加 \n
// }
NSData *data1 = [[NSData alloc] initWithBase64EncodedString:base64String1 options:NSDataBase64DecodingIgnoreUnknownCharacters];
// typedef NS_OPTIONS(NSUInteger, NSDataBase64DecodingOptions) {
// NSDataBase64DecodingIgnoreUnknownCharacters = 1UL << 0// 没的选，自动识别了
// }
- data <-> base64data
// 与 string 转换类似
NSData *base64Data = [data base64EncodedDataWithOptions:NSDataBase64Encoding64CharacterLineLength];
NSData *data5 = [[NSData alloc] initWithBase64EncodedData:base64Data options:NSDataBase64DecodingIgnoreUnknownCharacters];
Bytes 处理
- 准备数据
int len = 10;
Byte *bytes1 = malloc(sizeof(Byte) * len);
bytes1[0] = 0x00;
bytes1[1] = 0x01;
bytes1[2] = 0x02;
bytes1[3] = 0x03;
bytes1[4] = 0x04;
bytes1[5] = 0x05;
bytes1[6] = 0x06;
bytes1[7] = 0x07;
bytes1[8] = 0x08;
bytes1[9] = 0x09;
NSData *data = [NSData dataWithBytes:bytes1 length:len];
- 获取完整 bytes[]
Byte *dataBytes = (Byte *)data.bytes;
NSString *newHexStr = [NSString stringWithFormat:@"%x",dataBytes[1]&0xff];///16进制数
NSLog(@"%@", newHexStr);
- 获取部分 bytes[]
Byte *subBytes1 = malloc(sizeof(Byte) * 10);
[data getBytes:subBytes1 length:10];
NSLog(@"%@", [NSData dataWithBytes:subBytes1 length:10]);
Byte *subBytes2 = malloc(sizeof(Byte) * 3);
[data getBytes:subBytes2 range:NSMakeRange(2, 3)];
NSLog(@"%@", [NSData dataWithBytes:subBytes2 length:3]);
- 遍历（简单测试发现，byteRange 就是完整 data，拼接的复杂 data 会遍历出来？暂时不清楚）
[data enumerateByteRangesUsingBlock:^(const void * _Nonnull bytes, NSRange byteRange, BOOL * _Nonnull stop) {
NSLog(@"%@", NSStringFromRange(byteRange));
NSLog(@"%s", bytes);
}];
数据查找
- 准备数据
int len1 = 20;
Byte *bytes1 = malloc(sizeof(Byte) * len1);
bytes1[0] = 0x00;
bytes1[1] = 0x01;
bytes1[2] = 0x02;
bytes1[3] = 0x03;
bytes1[4] = 0x04;
bytes1[5] = 0x05;
bytes1[6] = 0x06;
bytes1[7] = 0x07;
bytes1[8] = 0x08;
bytes1[9] = 0x09;
bytes1[10] = 0x00;
bytes1[11] = 0x01;
bytes1[12] = 0x02;
bytes1[13] = 0x03;
bytes1[14] = 0x04;
bytes1[15] = 0x05;
bytes1[16] = 0x06;
bytes1[17] = 0x07;
bytes1[18] = 0x08;
bytes1[19] = 0x09;
NSData *data1 = [NSData dataWithBytes:bytes1 length:len1];
- 获取部分数据
NSData *subData = [data1 subdataWithRange:NSMakeRange(2, 3)];
- 查找部分数据的范围（可选条件）
// typedef NS_OPTIONS(NSUInteger, NSDataSearchOptions) {
// NSDataSearchBackwards = 1UL << 0, // 倒序
// NSDataSearchAnchored = 1UL << 1 // 类似前缀（结合倒序用就是后缀）
// }
- 正向查找
int len2 = 3;
Byte *bytes2 = malloc(sizeof(Byte) * len2);
bytes2[0] = 0x01;
bytes2[1] = 0x02;
bytes2[2] = 0x03;
NSData *data2 = [NSData dataWithBytes:bytes2 length:len2];
NSRange range2 = [data1 rangeOfData:data2 options:0 range:NSMakeRange(0, 20)];
- 反向查找
int len3 = 3;
Byte *bytes3 = malloc(sizeof(Byte) * len3);
bytes3[0] = 0x06;
bytes3[1] = 0x07;
bytes3[2] = 0x08;
NSData *data3 = [NSData dataWithBytes:bytes3 length:len3];
NSRange range3 = [data1 rangeOfData:data3 options:NSDataSearchBackwards range:NSMakeRange(0, 20)];
- 前缀
int len4 = 3;
Byte *bytes4 = malloc(sizeof(Byte) * len4);
bytes4[0] = 0x01;
bytes4[1] = 0x02;
bytes4[2] = 0x03;
NSData *data4 = [NSData dataWithBytes:bytes4 length:len4];
NSRange range4 = [data1 rangeOfData:data4 options:NSDataSearchAnchored range:NSMakeRange(1, 19)];
- 后缀
int len5 = 3;
Byte *bytes5 = malloc(sizeof(Byte) * len5);
bytes5[0] = 0x06;
bytes5[1] = 0x07;
bytes5[2] = 0x08;
NSData *data5 = [NSData dataWithBytes:bytes5 length:len5];
NSRange range5 = [data1 rangeOfData:data5 options:NSDataSearchAnchored | NSDataSearchBackwards range:NSMakeRange(0, 19)];
其他
BOOL iseq = [data1 isEqualToData:data2];
NSInteger len = data1.length;
NSString *desc = data1.description;