From ea765437ef52e86f3f35ee421cde843d20c6fc31 Mon Sep 17 00:00:00 2001
From: Matthew Chen <matthew@signal.org>
Date: Fri, 3 Aug 2018 10:25:22 -0400
Subject: [PATCH 1/3] Improve date formatting perf.

---
 Signal/src/util/DateUtil.m | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/Signal/src/util/DateUtil.m b/Signal/src/util/DateUtil.m
index ad9c954bf..9f74a0195 100644
--- a/Signal/src/util/DateUtil.m
+++ b/Signal/src/util/DateUtil.m
@@ -259,14 +259,20 @@ static NSString *const DATE_FORMAT_WEEKDAY = @"EEEE";
 
 + (NSString *)formatDateShort:(NSDate *)date
 {
+    OWSAssertIsOnMainThread();
     OWSAssert(date);
 
+    NSDate *now = [NSDate date];
+    NSInteger dayDifference = [self daysFromFirstDate:date toSecondDate:now];
+    BOOL dateIsOlderThanToday = dayDifference > 0;
+    BOOL dateIsOlderThanOneWeek = dayDifference > 6;
+
     NSString *dateTimeString;
     if (![DateUtil dateIsThisYear:date]) {
         dateTimeString = [[DateUtil dateFormatter] stringFromDate:date];
-    } else if ([DateUtil dateIsOlderThanOneWeek:date]) {
+    } else if (dateIsOlderThanOneWeek) {
         dateTimeString = [[DateUtil monthAndDayFormatter] stringFromDate:date];
-    } else if ([DateUtil dateIsOlderThanToday:date]) {
+    } else if (dateIsOlderThanToday) {
         dateTimeString = [[DateUtil shortDayOfWeekFormatter] stringFromDate:date];
     } else {
         dateTimeString = [[DateUtil timeFormatter] stringFromDate:date];

From 21c630c0958fa072ee960ab7d8037929dd2bb257 Mon Sep 17 00:00:00 2001
From: Matthew Chen <matthew@signal.org>
Date: Fri, 3 Aug 2018 10:25:38 -0400
Subject: [PATCH 2/3] Ignore redundant body text view updates; cache body text
 view size.

---
 .../Cells/OWSMessageTextView.m                | 63 +++++++++++++++++++
 1 file changed, 63 insertions(+)

diff --git a/Signal/src/ViewControllers/ConversationView/Cells/OWSMessageTextView.m b/Signal/src/ViewControllers/ConversationView/Cells/OWSMessageTextView.m
index f2dd320e5..5626d0a8a 100644
--- a/Signal/src/ViewControllers/ConversationView/Cells/OWSMessageTextView.m
+++ b/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

From 4d2bdf9bd0b019822d8f24995a27838bd018e141 Mon Sep 17 00:00:00 2001
From: Matthew Chen <matthew@signal.org>
Date: Fri, 3 Aug 2018 13:33:35 -0400
Subject: [PATCH 3/3] Respond to CR.

---
 .../ViewControllers/ConversationView/Cells/OWSMessageTextView.m | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Signal/src/ViewControllers/ConversationView/Cells/OWSMessageTextView.m b/Signal/src/ViewControllers/ConversationView/Cells/OWSMessageTextView.m
index 5626d0a8a..2ac36ade5 100644
--- a/Signal/src/ViewControllers/ConversationView/Cells/OWSMessageTextView.m
+++ b/Signal/src/ViewControllers/ConversationView/Cells/OWSMessageTextView.m
@@ -93,7 +93,7 @@ NS_ASSUME_NONNULL_BEGIN
         return;
     }
     [super setTextColor:textColor];
-    self.cachedSize = nil;
+    // No need to clear cached size here.
 }
 
 - (void)setFont:(nullable UIFont *)font