3.NSData

NSData

类型转换

NSString NSData

NSData *data = [str dataUsingEncoding:NSUTF8StringEncoding];
NSString * str = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];

NSDictionary NSData -JSON

NSData *data = [NSJSONSerialization dataWithJSONObject:dic options:NSJSONWritingPrettyPrinted error:nil];
NSDictionary *dic = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:nil];

NSDictionary NSData

NSMutableData *data= [[NSMutableData alloc] init];
NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData: data];
[archiver encodeObject:dic forKey:@"Some Key Value"];
[archiver finishEncoding];
NSLog(@"%@",data);

NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:dic2data];
NSDictionary *dic= [unarchiver decodeObjectForKey:@"Some Key Value"];
[unarchiver finishDecoding];
NSLog(@"%@",dic);

NSData 、Byte

NSString *testString = @"1234567890";
NSData *testData = [testString dataUsingEncoding: NSUTF8StringEncoding];
Byte *testByte = (Byte *)[testData bytes];

　　　Byte byte[] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23};
NSData *data = [[NSData alloc] initWithBytes:byte length:24];

NSArray转NSData

NSData *data= [NSKeyedArchiver archivedDataWithRootObject:array];

NSData转UIImage

UIImage *image = [UIImage imageWithData: data];

文件读写

//将文件的内容读入内存缓冲区
NSFileManager *fileManager = [[NSFileManager alloc]init];
NSData *fileData = [fileManager contentsAtPath:path];

　　//将缓冲区的内容写入到一个文件中
NSFileManager *fileManager = [[NSFileManager alloc]init];
[fileManager createFileAtPath:path contents:fileData attributes:nil];