如何在服务器上检索二进制格式的iPhone图像

在服务器中，图像以二进制格式存储。我必须使用json在iphone中检索图像。我该怎么做？是否也可以使用NSData执行此操作

您必须使用json解析从服务器获取二进制值，然后将该字符串转换为NSData

//MBBase64.h

@interface NSData (MBBase64)

+ (id)dataWithBase64EncodedString:(NSString *)string;     //  Padding '=' characters are optional. Whitespace is ignored.

@end


//MBBase64.m

static const char encodingTable[] =     "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

@implementation NSData (MBBase64)

+ (id)dataWithBase64EncodedString:(NSString *)string;
{
    if (string == nil)
        [NSException raise:NSInvalidArgumentException format:nil];
    if ([string length] == 0)
        return [NSData data];

    static char *decodingTable = NULL;
    if (decodingTable == NULL)
    {
        decodingTable = malloc(256);
        if (decodingTable == NULL)
            return nil;
        memset(decodingTable, CHAR_MAX, 256);
        NSUInteger i;
        for (i = 0; i < 64; i++)
            decodingTable[(short)encodingTable[i]] = i;
        }    

    const char *characters = [string cStringUsingEncoding:NSASCIIStringEncoding];
    if (characters == NULL)     //  Not an ASCII string!
        return nil;
    char *bytes = malloc((([string length] + 3) / 4) * 3);
    if (bytes == NULL)
        return nil;
    NSUInteger length = 0;

    NSUInteger i = 0;
    while (YES)
    {
        char buffer[4];
        short bufferLength;
        for (bufferLength = 0; bufferLength < 4; i++)
        {
            if (characters[i] == '\0')
                break;
            if (isspace(characters[i]) || characters[i] == '=')
                continue;
                buffer[bufferLength] = decodingTable[(short)characters[i]];
            if (buffer[bufferLength++] == CHAR_MAX)      //  Illegal character!
            {
                free(bytes);
                return nil;
            }
        }

        if (bufferLength == 0)
            break;
        if (bufferLength == 1)      //  At least two characters are needed to produce one byte!
        {
            free(bytes);
            return nil;
        }

        //  Decode the characters in the buffer to bytes.
        bytes[length++] = (buffer[0] << 2) | (buffer[1] >> 4);
        if (bufferLength > 2)
            bytes[length++] = (buffer[1] << 4) | (buffer[2] >> 2);
    if (bufferLength > 3)
        bytes[length++] = (buffer[2] << 6) | buffer[3];
    }

    realloc(bytes, length);
    return [NSData dataWithBytesNoCopy:bytes length:length];
}

@end

这是用于将base64字符串转换为NSData的标准代码

//MBBase64.h

@interface NSData (MBBase64)

+ (id)dataWithBase64EncodedString:(NSString *)string;     //  Padding '=' characters are optional. Whitespace is ignored.

@end


//MBBase64.m

static const char encodingTable[] =     "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

@implementation NSData (MBBase64)

+ (id)dataWithBase64EncodedString:(NSString *)string;
{
    if (string == nil)
        [NSException raise:NSInvalidArgumentException format:nil];
    if ([string length] == 0)
        return [NSData data];

    static char *decodingTable = NULL;
    if (decodingTable == NULL)
    {
        decodingTable = malloc(256);
        if (decodingTable == NULL)
            return nil;
        memset(decodingTable, CHAR_MAX, 256);
        NSUInteger i;
        for (i = 0; i < 64; i++)
            decodingTable[(short)encodingTable[i]] = i;
        }    

    const char *characters = [string cStringUsingEncoding:NSASCIIStringEncoding];
    if (characters == NULL)     //  Not an ASCII string!
        return nil;
    char *bytes = malloc((([string length] + 3) / 4) * 3);
    if (bytes == NULL)
        return nil;
    NSUInteger length = 0;

    NSUInteger i = 0;
    while (YES)
    {
        char buffer[4];
        short bufferLength;
        for (bufferLength = 0; bufferLength < 4; i++)
        {
            if (characters[i] == '\0')
                break;
            if (isspace(characters[i]) || characters[i] == '=')
                continue;
                buffer[bufferLength] = decodingTable[(short)characters[i]];
            if (buffer[bufferLength++] == CHAR_MAX)      //  Illegal character!
            {
                free(bytes);
                return nil;
            }
        }

        if (bufferLength == 0)
            break;
        if (bufferLength == 1)      //  At least two characters are needed to produce one byte!
        {
            free(bytes);
            return nil;
        }

        //  Decode the characters in the buffer to bytes.
        bytes[length++] = (buffer[0] << 2) | (buffer[1] >> 4);
        if (bufferLength > 2)
            bytes[length++] = (buffer[1] << 4) | (buffer[2] >> 2);
    if (bufferLength > 3)
        bytes[length++] = (buffer[2] << 6) | buffer[3];
    }

    realloc(bytes, length);
    return [NSData dataWithBytesNoCopy:bytes length:length];
}

@end

---

是的，您需要将二进制数据转换为NSData，如下所示：

NSData *imgData = [NSData dataWithBase64EncodedString:yourelement];
UIImage *theImg = [UIImage imageWithData:imgData];

---

您需要这里提供的MBBase64类：

对于API后端，您使用的是哪种语言php或其他任何东西？为什么不接受答案？有什么不对吗？