I am making a turn-based game where I have stored an integer variable 'points' into NSData, which is then stored by gamecenter. So far I am doing this as follows:
NSString *newString=[[NSString alloc] initWithFormat: #"%i", points];
NSData *data = [newString dataUsingEncoding:NSUTF8StringEncoding];
I need to store more variables into NSData *data. How can i do this?
I am now aware that you can store 2 integers in the string *newString by:
NSString *newString=[[NSString alloc] initWithFormat: #"%i, %i", points, otherInteger];
However I don't know how I would decode this as the string would be stored as one integer value following on from the last. It might not be the best implementation anyway so any suggestions would be appreciated.
You could do something like this:
// for encoding
int32_t points = ...;
int32_t otherInteger = ...;
NSMutableData *data = [NSMutableData data];
[data appendBytes:&points length:sizeof(int32_t)];
[data appendBytes:&otherInteger length:sizeof(int32_t)];
.
.
.
// for decoding
NSData *data = ...;
int32_t points;
int32_t otherInteger;
int index = 0;
NSRange range;
range = NSMakeRange(index, sizeof(int32_t));
[data getBytes:&points range:range];
index += sizeof(int32_t);
range = NSMakeRange(index, sizeof(int32_t));
[data getBytes:&otherInteger range:range];
index += sizeof(int32_t);
.
.
.
Related
Can anyone suggest a method to read bytes from NSData (like read function in #interface NSInputStream : NSStream)
How to read binary bytes in NSData? may help you:
NSString *path = #"…put the path to your file here…";
NSData * fileData = [NSData dataWithContentsOfFile: path];
const char* fileBytes = (const char*)[fileData bytes];
NSUInteger length = [fileData length];
NSUInteger index;
for (index = 0; index<length; index++) {
char aByte = fileBytes[index];
//Do something with each byte
}
You can also create an NSInputStream from an NSData object, if you need the read interface:
NSData *data = ...;
NSInputStream *readData = [[NSInputStream alloc] initWithData:data];
[readData open];
However, you should be aware that initWithData copies the contents of data.
One of the simplest ways is to use NSData getBytes:range:.
NSData *data = ...;
char buffer[numberOfBytes];
[data getBytes:buffer range:NSMakeRange(position, numberOfBytes)];
where position and length is the position you want to read from in NSData and the length is how many bytes you want to read. No need to copy.
Alex already mentioned NSData getBytes:range: but there is also NSData getBytes:length: which starts from the first byte.
NSData *data = ...;
char buffer[numberOfBytes];
[data getBytes:buffer length:numberOfBytes];
May way of doing that..
do not forget to free byte array after usage.
NSData* dat = //your code
NSLog(#"Receive from Peripheral: %#",dat);
NSUInteger len = [dat length];
Byte *bytedata = (Byte*)malloc(len);
[dat getBytes:bytedata length:len];
int p = 0;
while(p < len)
{
printf("%02x",bytedata[p]);
if(p!=len-1)
{
printf("-");
}//printf("%c",bytedata[p]);
p++;
}
printf("\n");
// byte array manipulation
free(bytedata);
NSString *string1 = #"<616263>";
I want to make this into NSData *data1 = <616263>;
so that when I
NSString *string2 = [[NSString alloc] initWithData:data1 encoding:NSUTF8StringEncoding];
NSLog(#"%#", string2);
Result: abc
would come out
p.s.
<616263>, this is data expression of #"abc"
The trick is converting 616263 to abc. Since you are starting with the ASCII representation of the character codes, you need to convert your NSString to an array of bytes (or your original data source to an array instead of saving it as an NSString in the first place).
NSString *string1 = #"616263";
// Make sure that buffer is big enough!
char sourceChars[7];
[string1 getCString:sourceChars maxLength:7 encoding:NSUTF8StringEncoding];
char destBuffer[3];
char charBuffer[3];
// Loop through sourceChars and convert the ASCII character groups to char's
// NOTE: I assume that these are always two character groupings per your example!
for (int index = 0; index < [string1 length]; index = index + 2) {
// Copy the next two digits into charBuffer
strncpy(charBuffer, &sourceChars[index], 2);
charBuffer[2] = '\0';
// convert charBuffer (ie 61) from hex to decimal
destBuffer[index / 2] = strtol(charBuffer, NULL, 16);
}
// destBuffer is properly formatted: init data1 with it.
NSData *data1 = [NSData dataWithBytes:destBuffer length:[string1 length]/2];
// Test
NSString *string2 = [[NSString alloc] initWithData:data1 encoding:NSUTF8StringEncoding];
NSLog(#"%#", string2); // Prints abc
I currently have an NSString containing hex values. I need to convert this NSString object into an NSData object, without changing its contents at all.
I use this code to "parse" the debug output of an NSData object (what you get in the console if you just NSLog an NSData object) back into NSData:
-(NSData*) bytesFromHexString:(NSString *)aString;
{
NSString *theString = [[aString componentsSeparatedByCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] componentsJoinedByString:nil];
NSMutableData* data = [NSMutableData data];
int idx;
for (idx = 0; idx+2 <= theString.length; idx+=2) {
NSRange range = NSMakeRange(idx, 2);
NSString* hexStr = [theString substringWithRange:range];
NSScanner* scanner = [NSScanner scannerWithString:hexStr];
unsigned int intValue;
if ([scanner scanHexInt:&intValue])
[data appendBytes:&intValue length:1];
}
return data;
}
It's not my most robust code, but it does the job of parsing [nsdata_object description].
I have some Bytes of image in my string and i want to draw it to UIImageView ...Here is my code
NSString* str= #"<89504e47 0d0a1a0a 0000000d 49484452 ........... 454e44ae 426082>";
NSData* data=[str dataUsingEncoding:NSUTF8StringEncoding];
NSLog(#"My NSDATA %#",data);
imageView.image=[UIImage imageWithData:data];
Now when i saw that printed data on console it is not in same format what i gave to that string..The output is something like.....
<3c383935 30346534 37203064 30613161..........
So my imageview show nothing..... please help
if question was: How to convert string data to image then this is answer.
NSData *imgData = [NSData dataWithContentsOfFile:[[NSBundle mainBundle] pathForResource:#"icon" ofType:#"png"]];
// set your string data into inputString var
NSString *inputString = [imgData description];
NSLog(#"input string %#",inputString);
// clearing string from trashes
NSString *dataStr = [inputString stringByTrimmingCharactersInSet:[NSCharacterSet characterSetWithCharactersInString:#"<>"]];
// separate by words of 4 bytes
NSArray *words = [dataStr componentsSeparatedByString:#" "];
// calculate number of bytes
NSArray *sizes = [words valueForKey:#"length"];
int sizeOfBytes = 0;
for (NSNumber *size in sizes) {
sizeOfBytes += [size intValue]/2;
}
int bytes[sizeOfBytes];
int counts = 0;
for (NSString *word in words) {
// convert each word from string to int
NSMutableString *ostr = [NSMutableString stringWithCapacity:[word length]];
while ([word length] > 0) {
[ostr appendFormat:#"%#", [word substringFromIndex:[word length] - 2]];
word = [word substringToIndex:[word length] - 2];
}
NSScanner *scaner = [NSScanner scannerWithString:ostr];
unsigned int val;
[scaner scanHexInt:&val];
bytes[counts] = val;
counts++;
}
// get NSData form c array
NSData* data = [NSData dataWithBytes:bytes length:sizeOfBytes];
NSLog(#"My NSDATA %#",data);
// your image is ready
UIImage *image = [UIImage imageWithData:data];
NSLog(#"image: %#",image);
what you are seeing in NSLog output are the ASCII codes of the string characters.
for example:
NSString* str = #"A";
NSData* data=[str dataUsingEncoding:NSUTF8StringEncoding];
NSLog(#"%#",data);
you will see something like:
<41....
that's because 0x41 is the code for letter A.
Same is happening with your string.
The data is exactly what you're feeding it: a simple string (printed as raw byte values). But I guess your input string is a hexdump and you manually need to turn into bytes.
I'm getting an HTML file as NSData and need to extract some parts of it. For that I need to convert it to NSString with UTF8 encoding. The thing is that this conversion fails, probably because the NSData contains bytes that are invalid for UTF8. I have tried to get the byte array of the data and go over it, but each time I come across non ASCII character (hebrew letters for example) I get jibrish.
Help will be appreciated.
UPDATE:
To Gordon - the NSData generated like that:
NSData *theData = [NSURLConnection sendSynchronousRequest:theRequest returningResponse:&theResponse error:&theError];
When I say that the conversion fails I mean that
[[NSString alloc] initWithData:temp encoding:NSUTF8StringEncoding]
returns nil
To Ed - Here is my code (I got the Byte array from NSData, found what I need, and constructed another Byte array from that - turned it to NSData and then attempted to convert it to NSString... sounds kinda complicated...)
-(NSString *)UTF8StringFromData:(NSData *)theData{
Byte *arr = [theData bytes];
NSUInteger begin1 = [self findIndexOf:#"<li>" bArr:arr size:[theData length]]+4;
NSUInteger end1 = [self findIndexOf:#"</li></ol>" bArr:arr size:[theData length]];
Byte *arr1 = (Byte *)malloc(sizeof(Byte)*((end1-begin1+1)));
NSLog(#"%d %d",begin1, end1);
int j = 0;
for (int i = begin1; i < end1; i++){
arr1[j] = arr[i];
j++;
}
arr1[j]='\0';
NSData *temp = [NSData dataWithBytes:arr1 length:j];
return [[NSString alloc] initWithData:temp encoding:NSUTF8StringEncoding];
}
I know this is an old topic but it came up when I was looking for the solution today. I've solved it now so I'm just posting it for others who might run into this page looking for a solution.
Here's what I do in an asynchronous request:
I first store the text encoding name in connection:didReceiveResponse using
encodingName = [[NSString alloc] initWithString:[response textEncodingName]];
Then later in my connectionDidFinishLoading method I used
NSStringEncoding encoding = CFStringConvertEncodingToNSStringEncoding(CFStringConvertIANACharSetNameToEncoding((CFStringRef) encodingName));
NSString *payloadAsString = [[NSString alloc] initWithData:receivedData encoding:encoding];
To Gordon - the NSData generated like that:
NSData *theData = [NSURLConnection sendSynchronousRequest:theRequest returningResponse:&theResponse error:&theError];
When I say that the conversion fails I mean that
[[NSString alloc] initWithData:temp encoding:NSUTF8StringEncoding]
returns nil
To Ed - Here is my code (I got the Byte array from NSData, found what I need, and constructed another Byte array from that - turned it to NSData and then attempted to convert it to NSString... sounds kinda complicated...)
-(NSString *)UTF8StringFromData:(NSData *)theData{
Byte *arr = [theData bytes];
NSUInteger begin1 = [self findIndexOf:#"<li>" bArr:arr size:[theData length]]+4;
NSUInteger end1 = [self findIndexOf:#"</li></ol>" bArr:arr size:[theData length]];
Byte *arr1 = (Byte *)malloc(sizeof(Byte)*((end1-begin1+1)));
NSLog(#"%d %d",begin1, end1);
int j = 0;
for (int i = begin1; i < end1; i++){
arr1[j] = arr[i];
j++;
}
arr1[j]='\0';
NSData *temp = [NSData dataWithBytes:arr1 length:j];
return [[NSString alloc] initWithData:temp encoding:NSUTF8StringEncoding];
}
have you checked the charset= in the HTTP headers and/or the document itself? The most likely reason for the conversion to fail is because the bytes don't represent a valid UTF-8 string.
I'm not sure if you're aware, you don't really need to copy the array to another array before putting it into the new NSData object.
-(NSString *)UTF8StringFromData:(NSData *)theData {
Byte *arr = [theData bytes];
NSUInteger begin1 = [self findIndexOf:#"<li>" bArr:arr size:[theData length]]+4;
NSUInteger end1 = [self findIndexOf:#"</li></ol>" bArr:arr size:[theData length]];
Byte *arr1 = arr + begin1;
NSData *temp = [NSData dataWithBytes:arr1 length:end1 - begin1];
return [[NSString alloc] initWithData:temp encoding:NSUTF8StringEncoding];
}
As for your particular problem, I would try looking through the data manually using the debugger. Put a breakpoint after you have your array (arr1). When you hit it, open up the GDB console and try this:
print (char *)arr1
With your code, it should print out the string you're trying to get. (With the code I gave above, it won't stop after the . It'll just keep going).
If the result is not what you expect, then there's something wrong with the data, or perhaps with your begin1 and end1 boundaries.