GraphicsContext on a string to print to the problem

 
+ (Void) generatePDFByImg: (UIImage *) img andText: (NSString *) text 
{
/ / Self.toolBar.hidden = YES; 
/ / NSString * text = @ "puma are large cat-like animals which are found in Americ"; 

CGSize pdfSize; 
pdfSize.height = 460; 
pdfSize.width = 320; 

UIGraphicsBeginImageContext ([[UIScreen mainScreen] bounds]. Size); 
/ / [Self.view.layer renderInContext: UIGraphicsGetCurrentContext ()]; 
/ / UIImage * pdfImage = UIGraphicsGetImageFromCurrentImageContext (); 
/ / UIGraphicsEndImageContext (); 
/ / Self.iiimagev.image = pdfImage; 

/ / UIImage * pdfImage = [UIImage imageNamed: @ "10074136.jpg"]; 

NSMutableData * outputData = [[NSMutableData alloc] init]; 
CGDataConsumerRef dataConsumer = CGDataConsumerCreateWithCFData ((__bridge CFMutableDataRef) outputData); 
CFMutableDictionaryRef attrDictionary = NULL; 
attrDictionary = CFDictionaryCreateMutable (NULL, 0, & kCFTypeDictionaryKeyCallBacks, & kCFTypeDictionaryValueCallBacks); 

CGContextRef pdfContext = CGPDFContextCreate (dataConsumer, NULL, attrDictionary); 
CFRelease (dataConsumer); 
CFRelease (attrDictionary); 
UIImage * myUIImage = img; 
CGImageRef pageImage = [myUIImage CGImage]; 
CGPDFContextBeginPage (pdfContext, NULL); 
NSLog (@ "[myUIImage size]. Width =% f", [myUIImage size]. Width); 
NSLog (@ "[myUIImage size]. Height =% f", [myUIImage size]. Height); 
CGContextDrawImage (pdfContext, CGRectMake (0, [[UIScreen mainScreen] bounds]. Size.height, ([myUIImage size]. Width) * 2, ([myUIImage size]. Height) * 2), pageImage); 
/ / NSLog (@ "[myUIImage size]. Width =% f", [myUIImage size]. Width); 
/ / NSLog (@ "[myUIImage size]. Height =% f", [myUIImage size]. Height); 
/ / CGContextDrawImage (pdfContext, CGRectMake (0, 0, [myUIImage size]. Width, [myUIImage size]. Height), pageImage); 
/ / CGContextSetTextDrawingMode (pdfContext, kCGTextFill); 
/ / [Text drawInRect: CGRectMake ([myUIImage size]. Width, [myUIImage size]. Width, 30, 80) withFont: [UIFont boldSystemFontOfSize: 15]]; 

NSString * str = [NSString stringWithFormat: @ "pulma is lager cat-like animals:% @ seconds", @ "65555"]; 

/ / Select the font is 16pt Helvetica 
CGContextSelectFont (pdfContext, "Helvetica", 16, kCGEncodingMacRoman); 
CGContextSetTextDrawingMode (pdfContext, kCGTextFill); / / set the drawing mode 
/ / Set the text color to black 
CGContextSetRGBFillColor (pdfContext, 0.0, 0.0, 200.0, 1.0); 
/ / Convert str is a C string and display it 

CGContextShowTextAtPoint (pdfContext, 10, 10, [str cStringUsingEncoding: [NSString defaultCStringEncoding]], str.length); 

/ / CGContextRestoreGState (pdfContext); / / Restore the context 

CGPDFContextEndPage (pdfContext); 
CGPDFContextClose (pdfContext); 
CGContextRelease (pdfContext); 
/ / NSString * pdfFileName = [self getPDFFileName]; 
NSString * pdfFileName = [NSHomeDirectory () stringByAppendingPathComponent: @ "mytestpdf.pdf"]; 
[OutputData writeToFile: pdfFileName atomically: YES]; 

} 

This code will generate an image and some text to PDF, use CGContextShowTextAtPoint (pdfContext, 10, 10, [str cStringUsingEncoding: [NSString defaultCStringEncoding]], str.length);
This method can be generated in English, but were unable to generate the Chinese, and I wanted to use [str drawAtPoint: point withFont: [UIFont systemFontOfSize: 16]] to achieve, but after the call does not appear in the PDF text
Which god know?