iOS cvVideoCamera constantly refocusing

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I'm trying to port a rectangle detection project onto iOS, and I've noticed that the CvVideoCamera takes a very long time to focus, and is generally blurry (which negatively affects the detection). Is there any way around this? How can I, for example, obtain camera inputs that are as clear as the native iOS camera application?

If there are also ways to mitigate the loss of accuracy (through image sharpening maybe) that would not affect the real-time nature of the app, that would also be great advice. Any help is appreciated!