Ignore redundant body text view updates; cache body text view size.

Signal/src/ViewControllers/ConversationView/Cells/OWSMessageTextView.m

@@ -7,6 +7,14 @@
 
 NS_ASSUME_NONNULL_BEGIN
 
+@interface OWSMessageTextView ()
+
+@property (nonatomic, nullable) NSValue *cachedSize;
+
+@end
+
+#pragma mark -
+
 @implementation OWSMessageTextView
 
 // Our message text views are never used for editing;
@@ -61,6 +69,61 @@ NS_ASSUME_NONNULL_BEGIN
     return result;
 }
 
+- (void)setText:(nullable NSString *)text
+{
+    if ([NSObject isNullableObject:text equalTo:self.text]) {
+        return;
+    }
+    [super setText:text];
+    self.cachedSize = nil;
+}
+
+- (void)setAttributedText:(nullable NSAttributedString *)attributedText
+{
+    if ([NSObject isNullableObject:attributedText equalTo:self.attributedText]) {
+        return;
+    }
+    [super setAttributedText:attributedText];
+    self.cachedSize = nil;
+}
+
+- (void)setTextColor:(nullable UIColor *)textColor
+{
+    if ([NSObject isNullableObject:textColor equalTo:self.textColor]) {
+        return;
+    }
+    [super setTextColor:textColor];
+    self.cachedSize = nil;
+}
+
+- (void)setFont:(nullable UIFont *)font
+{
+    if ([NSObject isNullableObject:font equalTo:self.font]) {
+        return;
+    }
+    [super setFont:font];
+    self.cachedSize = nil;
+}
+
+- (void)setLinkTextAttributes:(nullable NSDictionary<NSString *, id> *)linkTextAttributes
+{
+    if ([NSObject isNullableObject:linkTextAttributes equalTo:self.linkTextAttributes]) {
+        return;
+    }
+    [super setLinkTextAttributes:linkTextAttributes];
+    self.cachedSize = nil;
+}
+
+- (CGSize)sizeThatFits:(CGSize)size
+{
+    if (self.cachedSize) {
+        return self.cachedSize.CGSizeValue;
+    }
+    CGSize result = [super sizeThatFits:size];
+    self.cachedSize = [NSValue valueWithCGSize:result];
+    return result;
+}
+
 @end
 
 NS_ASSUME_NONNULL_END