How to load Sound Font - ios

Question

I'm having no luck loading a Sound Font file (.SF2) in my IOS app. I initially tried using Apple's code from Tech note TN2283
- (OSStatus) loadFromDLSOrSoundFont: (NSURL *)bankURL withPatch: (int)presetNumber {
OSStatus result = noErr;
// fill out a instrument data structure
AUSamplerInstrumentData instdata;
instdata.bankURL = (CFURLRef) bankURL;
instdata.instrumentType = kInstrumentType_DLSPreset;
instdata.bankMSB = kAUSampler_DefaultMelodicBankMSB;
instdata.bankLSB = kAUSampler_DefaultBankLSB;
instdata.presetID = (UInt8) presetNumber;
// set the kAUSamplerProperty_LoadPresetFromBank property
result = AudioUnitSetProperty(self.mySamplerUnit,
kAUSamplerProperty_LoadInstrument,
kAudioUnitScope_Global,
0,
&instdata,
sizeof(instdata));
// check for errors
NSCAssert (result == noErr,
#"Unable to set the preset property on the Sampler. Error code:%d '%.4s'",
(int) result,
(const char *)&result);
return result; }
But the compiler complains that 'No member named 'bankURL' in struct AUSamplerInstrumentData' which is true, the struct does not contain a 'bankURL' member??
I then came across the following code, by Apple I believe
- (OSStatus)loadSoundFont:(NSURL *)bankURL withPatch:(int)presetNumber
{
OSStatus result = noErr;
// fill out a bank preset data structure
AUSamplerBankPresetData bpdata;
bpdata.bankURL = (__bridge CFURLRef) bankURL;
bpdata.bankMSB = kAUSampler_DefaultMelodicBankMSB;
bpdata.bankLSB = kAUSampler_DefaultBankLSB;
bpdata.presetID = (UInt8) presetNumber;
// set the kAUSamplerProperty_LoadPresetFromBank property
result = AudioUnitSetProperty(self.samplerUnit,
kAUSamplerProperty_LoadPresetFromBank,
kAudioUnitScope_Global,
0,
&bpdata,
sizeof(bpdata));
// check for errors
NSCAssert (result == noErr,
#"Unable to set the preset property on the Sampler. Error code:%d '%.4s'",
(int) result,
(const char *)&result);
return result;
}
This all looks correct but when I attempt to load a sound font using this method such as follows
NSURL *SFURL = [[NSBundle mainBundle] URLForResource:#"YAMAHA DX7Piano" withExtension:#"SF2"];
[self loadSoundFont:url withPatch:0];
it throws the error "Unable to set the preset property on the Sampler.." This did lead me to think there was some error in how I specified the patch number, such as supplying a non-existent patch number. But I did eventually discover that the NSURL I was supplying was null, so I tried specifying the url as follows:
NSString *resources = [[NSBundle mainBundle] resourcePath];
NSURL *SFURL = [NSURL fileURLWithPath:[NSString stringWithFormat:#"%#/%#",resources,#"YAMAHA DX7Piano.SF2"]];
This has got me a step closer. I think I am now supplying a valid url to the sound font file in my app bundle. But it still is not working. My compiler now tells me
ERROR: [0x19a824310] 486: DLS/SF2 bank load failed
There is a piece of the puzzle missing and I can't see what.??

Answer 1

Well I found the solution. The Sound font wasn't loading. It wasn't loadoing because it was not added to the app bundle correctly. I had dragged it into resources but had to then add it to 'Copy bundle resources' in the project 'Build Phases'.