Replace attributed string height calculation with a more reliable implementation

Riot/Modules/MatrixKit/Models/Room/MXKRoomBubbleCellData.m

@@ -533,15 +533,7 @@
     CGFloat verticalInset = measurementTextView.textContainerInset.top + measurementTextView.textContainerInset.bottom;
     CGFloat horizontalInset = measurementTextView.textContainer.lineFragmentPadding * 2;
     
-    CGSize size = [attributedText boundingRectWithSize:CGSizeMake(_maxTextViewWidth - horizontalInset, CGFLOAT_MAX)
-                                               options:NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingUsesFontLeading | NSStringDrawingUsesDeviceMetrics
-                                               context:nil].size;
-    
-    //In iOS 7 and later, this method returns fractional sizes (in the size component of the returned rectangle);
-    // to use a returned size to size views, you must use raise its value to the nearest higher integer using the
-    // [ceil](https://developer.apple.com/documentation/kernel/1557272-ceil?changes=latest_major) function.
-    size.width = ceil(size.width);
-    size.height = ceil(size.height);
+    CGSize size = [self sizeForAttributedString:attributedText fittingWidth:_maxTextViewWidth - horizontalInset];
 
     // The result is expected to contain the textView textContainer's paddings. Add them back if necessary
     if (removeVerticalInset == NO) {
@@ -553,6 +545,27 @@
     return size;
 }
 
+// https://stackoverflow.com/questions/54497598/nsattributedstring-boundingrect-returns-wrong-height
+- (CGSize)sizeForAttributedString:(NSAttributedString *)attributedString fittingWidth:(CGFloat)width
+{
+    NSTextStorage *textStorage = [[NSTextStorage alloc] initWithAttributedString:attributedString];
+    
+    CGRect boundingRect = CGRectMake(0.0, 0.0, width, CGFLOAT_MAX);
+    
+    NSTextContainer *textContainer = [[NSTextContainer alloc] initWithSize:boundingRect.size];
+    textContainer.lineFragmentPadding = 0;
+
+    NSLayoutManager *layoutManager = [[NSLayoutManager alloc] init];
+    [layoutManager addTextContainer: textContainer];
+
+    [textStorage addLayoutManager:layoutManager];
+    [layoutManager glyphRangeForBoundingRect:boundingRect inTextContainer:textContainer];
+
+    CGRect rect = [layoutManager usedRectForTextContainer:textContainer];
+    
+    return CGRectIntegral(rect).size;
+}
+
 #pragma mark - Properties
 
 - (MXSession*)mxSession