- (__kindof UITableViewCell *)fd_templateCellForReuseIdentifier:(NSString *)identifier;

@interface UITableView (FDTemplateLayoutCell)

@interface UITableViewCell (FDTemplateLayoutCell)

/// Indicate this is a template layout cell for calculation only.
/// You may need this when there are non-UI side effects when configure a cell.
/// Like:
///   - (void)configureCell:(FooCell *)cell atIndexPath:(NSIndexPath *)indexPath {
///       cell.entity = [self entityAtIndexPath:indexPath];
///       if (!cell.fd_isTemplateLayoutCell) {
///           [self notifySomething]; // non-UI side effects
///       }
///   }
///
@property (nonatomic, assign) BOOL fd_isTemplateLayoutCell;

@implementation UITableViewCell (FDTemplateLayoutCell)

- (BOOL)fd_isTemplateLayoutCell {
    return [objc_getAssociatedObject(self, _cmd) boolValue];
}

- (void)setFd_isTemplateLayoutCell:(BOOL)isTemplateLayoutCell {
    objc_setAssociatedObject(self, @selector(fd_isTemplateLayoutCell), @(isTemplateLayoutCell), OBJC_ASSOCIATION_RETAIN);
}

        static const CGFloat systemAccessoryWidths[] = {
            [UITableViewCellAccessoryNone] = 0,
            [UITableViewCellAccessoryDisclosureIndicator] = 34,
            [UITableViewCellAccessoryDetailDisclosureButton] = 68,
            [UITableViewCellAccessoryCheckmark] = 40,
            [UITableViewCellAccessoryDetailButton] = 48
        };
        contentViewWidth -= systemAccessoryWidths[cell.accessoryType];

        // Add a hard width constraint to make dynamic content views (like labels) expand vertically instead
        // of growing horizontally, in a flow-layout manner.
        NSLayoutConstraint *widthFenceConstraint = [NSLayoutConstraint constraintWithItem:cell.contentView attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1.0 constant:contentViewWidth];
        [cell.contentView addConstraint:widthFenceConstraint];
        
        // Auto layout engine does its math
        fittingHeight = [cell.contentView systemLayoutSizeFittingSize:UILayoutFittingCompressedSize].height;
        [cell.contentView removeConstraint:widthFenceConstraint];

        // Try '- sizeThatFits:' for frame layout.
        // Note: fitting height should not include separator view.
        fittingHeight = [cell sizeThatFits:CGSizeMake(contentViewWidth, 0)].height;

- (__kindof UITableViewCell *)fd_templateCellForReuseIdentifier:(NSString *)identifier {
    NSAssert(identifier.length > 0, @"Expect a valid identifier - %@", identifier);
    
    NSMutableDictionary<NSString *, UITableViewCell *> *templateCellsByIdentifiers = objc_getAssociatedObject(self, _cmd);
    if (!templateCellsByIdentifiers) {
        templateCellsByIdentifiers = @{}.mutableCopy;
        objc_setAssociatedObject(self, _cmd, templateCellsByIdentifiers, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    }
    
    UITableViewCell *templateCell = templateCellsByIdentifiers[identifier];
    
    if (!templateCell) {
        templateCell = [self dequeueReusableCellWithIdentifier:identifier];
        NSAssert(templateCell != nil, @"Cell must be registered to table view for identifier - %@", identifier);
        templateCell.fd_isTemplateLayoutCell = YES;
        templateCell.contentView.translatesAutoresizingMaskIntoConstraints = NO;
        templateCellsByIdentifiers[identifier] = templateCell;
        [self fd_debugLog:[NSString stringWithFormat:@"layout cell created - %@", identifier]];
    }
    
    return templateCell;
}

typedef NSMutableArray<NSMutableArray<NSNumber *> *> FDIndexPathHeightsBySection;

@property (nonatomic, strong) FDIndexPathHeightsBySection *heightsBySectionForPortrait;
@property (nonatomic, strong) FDIndexPathHeightsBySection *heightsBySectionForLandscape;

    return UIDeviceOrientationIsPortrait([UIDevice currentDevice].orientation) ? self.heightsBySectionForPortrait: self.heightsBySectionForLandscape;

- (CGFloat)heightForIndexPath:(NSIndexPath *)indexPath {
    [self buildCachesAtIndexPathsIfNeeded:@[indexPath]];
    NSNumber *number = self.heightsBySectionForCurrentOrientation[indexPath.section][indexPath.row];
#if CGFLOAT_IS_DOUBLE
    return number.doubleValue;
#else
    return number.floatValue;
#endif
}

        [self methodSignatureForSelector:nil];

// We just forward primary call, in crash report, top most method in stack maybe FD's,
// but it's really not our bug, you should check whether your table view's data source and
// displaying cells are not matched when reloading.
static void __FD_TEMPLATE_LAYOUT_CELL_PRIMARY_CALL_IF_CRASH_NOT_OUR_BUG__(void (^callout)(void)) {
    callout();
}
#define FDPrimaryCall(...) do {__FD_TEMPLATE_LAYOUT_CELL_PRIMARY_CALL_IF_CRASH_NOT_OUR_BUG__(^{__VA_ARGS__});} while(0)

@implementation UITableView (FDIndexPathHeightCacheInvalidation)

- (void)fd_reloadDataWithoutInvalidateIndexPathHeightCache {
    FDPrimaryCall([self fd_reloadData];);
}

+ (void)load {
    // All methods that trigger height cache's invalidation
    SEL selectors[] = {
        @selector(reloadData),
        @selector(insertSections:withRowAnimation:),
        @selector(deleteSections:withRowAnimation:),
        @selector(reloadSections:withRowAnimation:),
        @selector(moveSection:toSection:),
        @selector(insertRowsAtIndexPaths:withRowAnimation:),
        @selector(deleteRowsAtIndexPaths:withRowAnimation:),
        @selector(reloadRowsAtIndexPaths:withRowAnimation:),
        @selector(moveRowAtIndexPath:toIndexPath:)
    };
    
    for (NSUInteger index = 0; index < sizeof(selectors) / sizeof(SEL); ++index) {
        SEL originalSelector = selectors[index];
        SEL swizzledSelector = NSSelectorFromString([@"fd_" stringByAppendingString:NSStringFromSelector(originalSelector)]);
        Method originalMethod = class_getInstanceMethod(self, originalSelector);
        Method swizzledMethod = class_getInstanceMethod(self, swizzledSelector);
        method_exchangeImplementations(originalMethod, swizzledMethod);
    }
}

        SEL originalSelector = selectors[index];
        SEL swizzledSelector = NSSelectorFromString([@"fd_" stringByAppendingString:NSStringFromSelector(originalSelector)]);
        Method originalMethod = class_getInstanceMethod(self, originalSelector);
        Method swizzledMethod = class_getInstanceMethod(self, swizzledSelector);
        method_exchangeImplementations(originalMethod, swizzledMethod);

@implementation UITableView (FDKeyedHeightCache)

- (FDKeyedHeightCache *)fd_keyedHeightCache {
    FDKeyedHeightCache *cache = objc_getAssociatedObject(self, _cmd);
    if (!cache) {
        cache = [FDKeyedHeightCache new];
        objc_setAssociatedObject(self, _cmd, cache, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    }
    return cache;
}

@end

@interface UITableView (FDTemplateLayoutCellDebug)