How to download blob from WKWebView

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Created Jun ’21

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I have developed an app that allows the user to validate himself on a website and, through a webview, navigate through it. In the event that the user tries to download a document through a link, it is stored on their device. The problem arises when the download url is of the type blob: // https: // .... To contemplate this case, I have tried to evaluate a javascript that allows obtaining the bytes of the document in base64 using the XMLHttpRequest object (analogously to how I have solved it in android), but in this case the onload method always the value 0 for the status attribute of the XMLHttpRequest object. Is there a solution to be able to download blob files from a WKWebView in swift?

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Answer 1

DouglasAmorim OP

Jul ’21

Hi, I went through the same problem as you. Here is the JS Script with I use to solve this problem:

""" (async function download() { javascript: var xhr = new XMLHttpRequest(); xhr.open('GET', '(absoluteUrl)', true); xhr.setRequestHeader('Content-type','application/octet-stream'); xhr.responseType = 'blob'; xhr.send(); xhr.onload = await function(e) { if (this.status == 200) { var blobFile = this.response; var reader = new FileReader(); reader.readAsDataURL(blobFile); reader.onloadend = function() { base64data = reader.result; window.webkit.messageHandlers.getBase64FromBlobData.postMessage(base64data); } } }; })(); """

I use this two links as reference:

https://www.programmersought.com/article/78896496442/
https://stackoverflow.com/questions/59083340/how-to-download-files-in-wkwebview

I hope it help you

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