Ensure HTML parsing always occurs on the main thread (#767)

kickstarter · Jul 30, 2019 · b41d2b8 · b41d2b8
1 parent 10094d1
commit b41d2b8
Showing 1 changed file with 61 additions and 40 deletions.
diff --git a/Library/String+SimpleHTML.swift b/Library/String+SimpleHTML.swift
@@ -21,44 +21,55 @@ public extension String {
     bold optionalBold: Attributes? = nil,
     italic optionalItalic: Attributes? = nil
   ) -> NSAttributedString? {
-    let baseFont = (base[NSAttributedString.Key.font] as? UIFont) ?? UIFont.systemFont(ofSize: 12.0)
+    func parsedHtml() -> NSAttributedString? {
+      let baseFont = (base[NSAttributedString.Key.font] as? UIFont) ?? UIFont.systemFont(ofSize: 12.0)
+
+      // If bold or italic are not specified we can derive them from `font`.
+      let bold = optionalBold ?? [NSAttributedString.Key.font: baseFont.bolded]
+      let italic = optionalItalic ?? [NSAttributedString.Key.font: baseFont.italicized]
+
+      guard let data = self.data(using: String.Encoding.utf8) else { return nil }
+
+      let options: [NSAttributedString.DocumentReadingOptionKey: Any] = [
+        NSAttributedString.DocumentReadingOptionKey.documentType: NSAttributedString.DocumentType.html,
+        NSAttributedString.DocumentReadingOptionKey.characterEncoding: String.Encoding.utf8.rawValue
+      ]
+      guard let string = try? NSMutableAttributedString(data: data, options: options, documentAttributes: nil)
+      else {
+        return nil
+      }
 
-    // If bold or italic are not specified we can derive them from `font`.
-    let bold = optionalBold ?? [NSAttributedString.Key.font: baseFont.bolded]
-    let italic = optionalItalic ?? [NSAttributedString.Key.font: baseFont.italicized]
+      // Sub all bold and italic fonts in the attributed html string
+      let stringRange = NSRange(location: 0, length: string.length)
+      string.beginEditing()
+      string
+        .enumerateAttribute(NSAttributedString.Key.font, in: stringRange, options: []) { value, range, _ in
 
-    guard let data = self.data(using: String.Encoding.utf8) else { return nil }
+          guard let htmlFont = value as? UIFont else { return }
+          let newAttributes: Attributes
 
-    let options: [NSAttributedString.DocumentReadingOptionKey: Any] = [
-      NSAttributedString.DocumentReadingOptionKey.documentType: NSAttributedString.DocumentType.html,
-      NSAttributedString.DocumentReadingOptionKey.characterEncoding: String.Encoding.utf8.rawValue
-    ]
-    guard let string = try? NSMutableAttributedString(data: data, options: options, documentAttributes: nil)
-    else {
-      return nil
-    }
+          if htmlFont.fontDescriptor.symbolicTraits.contains(.traitBold) {
+            newAttributes = bold
+          } else if htmlFont.fontDescriptor.symbolicTraits.contains(.traitItalic) {
+            newAttributes = italic
+          } else {
+            newAttributes = base
+          }
 
-    // Sub all bold and italic fonts in the attributed html string
-    let stringRange = NSRange(location: 0, length: string.length)
-    string.beginEditing()
-    string.enumerateAttribute(NSAttributedString.Key.font, in: stringRange, options: []) { value, range, _ in
+          string.addAttributes(newAttributes, range: range)
+        }
+      string.endEditing()
 
-      guard let htmlFont = value as? UIFont else { return }
-      let newAttributes: Attributes
+      return string
+    }
 
-      if htmlFont.fontDescriptor.symbolicTraits.contains(.traitBold) {
-        newAttributes = bold
-      } else if htmlFont.fontDescriptor.symbolicTraits.contains(.traitItalic) {
-        newAttributes = italic
-      } else {
-        newAttributes = base
+    if Thread.isMainThread {
+      return parsedHtml()
+    } else {
+      return DispatchQueue.main.sync {
+        parsedHtml()
       }
-
-      string.addAttributes(newAttributes, range: range)
     }
-    string.endEditing()
-
-    return string
   }
 
   /**
@@ -93,19 +104,29 @@ public extension String {
    - returns: A string with all HTML stripped.
    */
   func htmlStripped(trimWhitespace: Bool = true) -> String? {
-    guard let data = self.data(using: String.Encoding.utf8) else { return nil }
+    func parsedHtml() -> String? {
+      guard let data = self.data(using: String.Encoding.utf8) else { return nil }
 
-    let options: [NSAttributedString.DocumentReadingOptionKey: Any] = [
-      NSAttributedString.DocumentReadingOptionKey.documentType: NSAttributedString.DocumentType.html,
-      NSAttributedString.DocumentReadingOptionKey.characterEncoding: String.Encoding.utf8.rawValue
-    ]
+      let options: [NSAttributedString.DocumentReadingOptionKey: Any] = [
+        NSAttributedString.DocumentReadingOptionKey.documentType: NSAttributedString.DocumentType.html,
+        NSAttributedString.DocumentReadingOptionKey.characterEncoding: String.Encoding.utf8.rawValue
+      ]
 
-    let string = try? NSAttributedString(data: data, options: options, documentAttributes: nil)
-    let result = string?.string
+      let string = try? NSAttributedString(data: data, options: options, documentAttributes: nil)
+      let result = string?.string
 
-    if trimWhitespace {
-      return result?.trimmingCharacters(in: .whitespacesAndNewlines)
+      if trimWhitespace {
+        return result?.trimmingCharacters(in: .whitespacesAndNewlines)
+      }
+      return result
+    }
+
+    if Thread.isMainThread {
+      return parsedHtml()
+    } else {
+      return DispatchQueue.main.sync {
+        parsedHtml()
+      }
     }
-    return result
   }
 }