CODEWITHSUNDEEP
iosobjective-cccore-bluetooth
real 19
real 19

Reputation: 748

Convert Unsigned Int to Hexadecimal value

How can I convert a integer 6 digit number such as "1234674" to a hexadecimal 4 byte NSData in Objective-C ?

This is the part of our code that sends passkey:

#define HSL_PRIVATE_SERVICE_UUID 0xFF20 
#define HSL_PRIVATE_NEW_PASSKEY_UUID 0xFF35 
unsigned int newPassKey = [_confirmNewPassKey.text intValue];
NSLog(@"newPasskey %d", newPassKey);
NSData *d = [NSData dataWithBytes:&newPassKey length:sizeof(unsigned int)];
[_t writeValue:HSL_PRIVATE_SERVICE_UUID characteristicUUID:HSL_PRIVATE_NEW_PASSKEY_UUID p:_peripheral data:d];

I did an air capture comparing BTOOL versus iPhone passkey writes.

BTOOL (A simulator tool) wrote (the correct result) :

0x40e201

iPhone wrote(wrong data):

 0x0001e240

Not sure what is going on and how to fix it in the app so that the result matches what the Bluetooth device is expecting . I would like the result to be same as BTOOL one.

Upvotes: 0

Views: 1509

Answers (1)

rmaddy
rmaddy

Reputation: 318804

Try this:

uint32_t value = [_confirmNewPassKey.text intValue];
uint32_t swapped = CFSwapInt32HostToBig(value);
NSData *d = [NSData dataWithBytes:&swapped length:sizeof(swapped)];

This assumes you want big endian for the output.

Upvotes: 1

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