Base 64 image on IOS web viewer

hello to all of you. To start I want to apologize for my English.
I have a problem and I have been stuck for a long time.
My APP receives an image in base64 from gmail, this code is stored as a variable and I can see the image perfectly from the image component or from the web viewer, but in ios it does not load in the web viewer in any way. Does anyone have a solution to this?
Is there any other way to see large images where you can zoom in? I have tried canvas, but the problem is that the images cannot be updated once the APP has been compiled.