How to make a valid p12 file to be correctly impor

I've solved my previos problem of converting XML RSA private key to PEM file, but I run into another problem that I get null data when importing P12 private key. Following is my steps:

Convert PEM file to P12 file

openssl> pkcs12 -export -in rsa.pem -inkey rsa.pem -out rsa.p12 -nocerts

Read P12 file to iOS project

NSString *path = [[NSBundle bundleForClass:[self class]]    
                    pathForResource:@"MyPrivateKey" ofType:@"p12"];
NSData *p12data = [NSData dataWithContentsOfFile:path];
if (![self getPrivateKeyRef]) 
    RSAPrivateKey = getPrivateKeywithRawKey(p12data);

Import P12 Private Key

SecKeyRef getPrivateKeywithRawKey(NSData *pfxkeydata)
{ 
    NSMutableDictionary * options = [[[NSMutableDictionary alloc] init] autorelease];

    // Set the public key query dictionary
    //change to your .pfx  password here 
    [options setObject:@"MyPassword" forKey:(id)kSecImportExportPassphrase];

    CFArrayRef items = CFArrayCreate(NULL, 0, 0, NULL);

    OSStatus securityError = SecPKCS12Import((CFDataRef) pfxkeydata,
                                             (CFDictionaryRef)options, &items);

    CFDictionaryRef identityDict = CFArrayGetValueAtIndex(items, 0);
    SecIdentityRef identityApp =
    (SecIdentityRef)CFDictionaryGetValue(identityDict,
                                         kSecImportItemIdentity);
    //NSLog(@"%@", securityError);

    assert(securityError == noErr);
    SecKeyRef privateKeyRef;
    SecIdentityCopyPrivateKey(identityApp, &privateKeyRef);

    return privateKeyRef;

}

Thought there was no err(OSStatus value is 0), but the items array didn't get any identity data. I am wondering if i didn't get the correct p12 file format due to wrong OpenSSl usage. Has anyone successfully import p12 file? I've stuck in this problem for a couple of days, please give me advices if you got clues, thanks!

Hubert

I got some tips from the internet, and following is the steps to get iOS acceptable p12 key and certification file:

convert XML to PEM
Shell> compile XMLSpec2PEM.java
Shell> XMLSpec2PEM rsa.xml
save the output result to rsa.pem
(borrow from here)
convert PEM to RSA Private Key
OpenSSL> rsa -in rsa.pem -out rsaPrivate.key
Generate a certification request
OpenSSL> req -new -key rsaPrivate.key -out rsaCertReq.crt
(input some basic certification data)
Sign certification of the request
OpenSSL> x509 -req -days 3650 -in rsaCertReq.crt -signkey rsaPrivate.key -out rsaCert.crt
Convert the certification file format to DER (iOS acceptable format)
OpenSSL> x509 -outform der -in rsaCert.crt -out rsaCert.der
Generate PKCS12 Private key(iOS acceptable format)
OpenSSL> pkcs12 -export -out rsaPrivate.pfx -inkey rsaPrivate.key -in rsaCert.crt