Fix a retain cycle in render operation closure

Author: pjay

CHANGELOG.md

@@ -13,6 +13,10 @@ All notable changes to this project will be documented in this file.
   - Added by [William Entriken](https://github.com/fulldecent) in Regards to Issue
   [#76](https://github.com/fulldecent/FDWaveformView/issues/86).
 
+#### Fixed
+- Fixed a retain cycle in completion handler of waveform render operation
+  - Added by [Philippe Jayet](https://github.com/pjay)
+
 ---
 
 ## [2.2.0](https://github.com/fulldecent/FDWaveformView/releases/tag/2.2.0)

Source/FDWaveformView.swift

@@ -416,15 +416,17 @@ open class FDWaveformView: UIView {
         let imageSize = CGSize(width: widthInPixels, height: heightInPixels)
         let renderFormat = FDWaveformRenderFormat(type: waveformRenderType, wavesColor: .black, scale: desiredImageScale)
 
-        let waveformRenderOperation = FDWaveformRenderOperation(audioContext: audioContext, imageSize: imageSize, sampleRange: renderSamples, format: renderFormat) { image in
+        let waveformRenderOperation = FDWaveformRenderOperation(audioContext: audioContext, imageSize: imageSize, sampleRange: renderSamples, format: renderFormat) { [weak self] image in
             DispatchQueue.main.async {
-                self.renderForCurrentAssetFailed = (image == nil)
-                self.waveformImage = image
-                self.renderingInProgress = false
-                self.cachedWaveformRenderOperation = self.inProgressWaveformRenderOperation
-                self.inProgressWaveformRenderOperation = nil
-                self.setNeedsLayout()
-                self.delegate?.waveformViewDidRender?(self)
+                guard let strongSelf = self else { return }
+                
+                strongSelf.renderForCurrentAssetFailed = (image == nil)
+                strongSelf.waveformImage = image
+                strongSelf.renderingInProgress = false
+                strongSelf.cachedWaveformRenderOperation = self?.inProgressWaveformRenderOperation
+                strongSelf.inProgressWaveformRenderOperation = nil
+                strongSelf.setNeedsLayout()
+                strongSelf.delegate?.waveformViewDidRender?(strongSelf)
             }
         }
         self.inProgressWaveformRenderOperation = waveformRenderOperation