3.NSData

NSData

• 用於將數據塊傳遞給一個函數或方法
• 用於存儲二進制的數據類型

類型轉換

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轉NSData

    NSData *data= [NSKeyedArchiver archivedDataWithRootObject:array];

NSData轉UIImage

    UIImage *image = [UIImage imageWithData: data];

文件讀寫

    //將文件的內容讀入內存緩衝區
    NSFileManager *fileManager = [[NSFileManager alloc]init];
    NSData *fileData = [fileManager contentsAtPath:path];

　　//將緩衝區的內容寫入到一個文件中
    NSFileManager *fileManager = [[NSFileManager alloc]init];
    [fileManager createFileAtPath:path contents:fileData attributes:nil];