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POHow would I tint an image programmatically on the iPhone?
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  1. POHow would I tint an image programmatically on the iPhone?
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    copied!<p>I would like to tint an image with a color reference. The results should look like the Multiply blending mode in Photoshop, where <em>whites</em> would be replaced with <em>tint</em>:</p> <p><img src="https://i.stack.imgur.com/CqiUz.png" alt="alt text"></p> <p>I will be changing the color value continuously.</p> <p><strong>Follow up:</strong> I would put the code to do this in my ImageView's drawRect: method, right?</p> <p>As always, a <em>code snippet</em> would greatly aid in my understanding, as opposed to a link.</p> <p><strong>Update:</strong> Subclassing a UIImageView with the code <strong>Ramin</strong> suggested. </p> <p>I put this in viewDidLoad: of my view controller:</p> <pre><code>[self.lena setImage:[UIImage imageNamed:kImageName]]; [self.lena setOverlayColor:[UIColor blueColor]]; [super viewDidLoad]; </code></pre> <p>I see the image, but it is not being tinted. I also tried loading other images, setting the image in IB, and calling setNeedsDisplay: in my view controller.</p> <p><strong>Update</strong>: drawRect: is not being called.</p> <p><strong>Final update:</strong> I found an old project that had an imageView set up properly so I could test Ramin's code and it works like a charm!</p> <p><strong>Final, final update:</strong></p> <p>For those of you just learning about Core Graphics, here is the simplest thing that could possibly work.</p> <p>In your subclassed UIView:</p> <pre><code>- (void)drawRect:(CGRect)rect { CGContextRef context = UIGraphicsGetCurrentContext(); CGContextSetFillColor(context, CGColorGetComponents([UIColor colorWithRed:0.5 green:0.5 blue:0 alpha:1].CGColor)); // don't make color too saturated CGContextFillRect(context, rect); // draw base [[UIImage imageNamed:@"someImage.png"] drawInRect: rect blendMode:kCGBlendModeOverlay alpha:1.0]; // draw image } </code></pre>
 

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