Question

I’m working on an iPhone app that can create pictures and post them to Facebook and Instagram.

The correct size for Facebook photos seems to be 350×350, and indeed this code creates a 350×350 image exactly how I want:

-(UIImage *)createImage {
    UIImageView *v = [[UIImageView alloc] initWithFrame:CGRectMake(0, screenHeight/2-349, 349, 349)];
    v.image = [UIImage imageNamed:@"backgroundForFacebook.png"];  //"backgroundForFacebook.png" is 349x349.

    //This code adds some text to the image.

    CGSize dimensions = CGSizeMake(screenWidth, screenHeight);
    CGSize imageSize = [self.ghhaiku.text sizeWithFont:[UIFont fontWithName:@"Georgia"
                                                                       size:mediumFontSize]
                                     constrainedToSize:dimensions lineBreakMode:0];
    int textHeight = imageSize.height+16;
    UITextView *tv = [self createTextViewForDisplay:self.ghhaiku.text];
    tv.frame = CGRectMake((screenWidth/2)-(self.textWidth/2),s creenHeight/3.5,
                          self.textWidth/2 + screenWidth/2, textHeight*2);
    [v addSubview:tv];

    //End of text-adding code

    CGRect newRect = CGRectMake(0, screenHeight/2-349, 349, 349);
    UIGraphicsBeginImageContext(newRect.size);
    [[v layer] renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *myImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    [v removeFromSuperview];
    return myImage;
}

But when I use the same code to create an Instagram image, which needs to be 612×612, I get the text only, no background image:

-(UIImage *)createImageForInstagram {
    UIImageView *v = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 612, 612)];
    v.image = [UIImage imageNamed:@"backgroundForInstagram.png"];  //"backgroundForInstagram.png" is 612x612.

    //...text-adding code...

    CGRect newRect = CGRectMake(0, 0, 612, 612);
    UIGraphicsBeginImageContext(newRect.size);
    [[v layer] renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *myImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    [v removeFromSuperview];
    return myImage;
}

What am I doing wrong, and how do I fix it?

(While I’m at it, I’ll also say that I’m very new to using graphic contexts, so if there’s any awkwardness in the code I’d appreciate your pointing it out.)

EDIT: Now I’ve reduced the two methods to one, and this time I don’t even get the text. Argh!

-(UIImage *)addTextToImage:(UIImage *)myImage withFontSize:(int)sz {
    NSString *string=self.displayHaikuTextView.text;
    NSString *myWatermarkText = [string stringByAppendingString:@"\n\n\t--haiku.com"];
    NSDictionary *attrs = [NSDictionary dictionaryWithObjectsAndKeys:[UIFont fontWithName:@"Georgia" 
                                                                                     size:sz],
                                                                     NSFontAttributeName, 
                                                                     nil];
    NSAttributedString *attString = [[NSAttributedString alloc] initWithString:myWatermarkText attributes:attrs];
    UIGraphicsBeginImageContextWithOptions(myImage.size,NO,1.0);
    [myImage drawAtPoint: CGPointZero];
    NSString *longestLine = ghv.listOfLines[1];
    CGSize sizeOfLongestLine = [longestLine sizeWithFont:[UIFont fontWithName:@"Georgia" size:sz]];
    CGSize siz = CGSizeMake(sizeOfLongestLine.width, sizeOfLongestLine.height*5);
    [attString drawAtPoint: CGPointMake(myImage.size.width/2 - siz.width/2, myImage.size.height/2-siz.height/2)];
    myImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return myImage;
}

When I pass the arguments [UIImage imageNamed:"backgroundForFacebook.png"] (an image 349×349) and 12, everything is fine. I get the picture. When I pass the arguments [UIImage imageNamed:"backgroundForInstagram.png"] (an image 612×612) and 24, nothing doing.

Right now I’m just putting the text on the smaller image (@”backgroundForFacebook.png”) and then resizing it, but that makes the text blurry, which I don’t like.

EDIT: Just to cover the basics, here are images of 1) the method in which I call this method (to check the spelling) and 2) the Supporting Files and the Build Phases (to show the image is actually there). I also tried assigning longestLine a non-variable NSString. No luck. 🙁

FURTHER EDIT: Okay, logging the size and scale of the images as I go during addTextToImage: above, here’s what I get for the smaller image, the one that’s working:

2013-02-04 22:24:09.588 GayHaikuTabbed[38144:c07] 349.000000, 349.000000, 1.000000

And here’s what I get for the larger image–it’s a doozy.

Feb  4 22:20:36 Joels-MacBook-Air.local GayHaikuTabbed[38007] <Error>: CGContextGetFontRenderingStyle: invalid context 0x0
Feb  4 22:20:36 Joels-MacBook-Air.local GayHaikuTabbed[38007] <Error>: CGContextSetFillColorWithColor: invalid context 0x0

//About thirty more of these.

Feb  4 22:20:36 Joels-MacBook-Air.local GayHaikuTabbed[38007] <Error>: CGBitmapContextCreate: unsupported parameter combination: 0 integer bits/component; 0 bits/pixel; 0-component color space; kCGImageAlphaNoneSkipLast; 2448 bytes/row.
Feb  4 22:20:36 Joels-MacBook-Air.local GayHaikuTabbed[38007] <Error>: CGContextDrawImage: invalid context 0x0
Feb  4 22:20:36 Joels-MacBook-Air.local GayHaikuTabbed[38007] <Error>: CGBitmapContextCreateImage: invalid context 0x0

Answer 1

i always back up to the obvious questions:

• is your image actually properly called/spelled backgroundForInstagram.png?
• have you properly added it to your project?
• when added, did it copied to the device in the copy steps of the build phases?
• what’s in the ghv at the time of the call in the edited code?
• what’s in item[1] of ghv.lines at the time of that rendering?

these are the things i would look at in terms of debugging this code.