UITableView-FDTemplateLayoutCell

Overview

Template auto layout cell for automatically UITableViewCell height calculating.

Basic usage

If you have a self-satisfied cell, then all you have to do is:

#import "UITableView+FDTemplateLayoutCell.h"

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
    return [tableView fd_heightForCellWithIdentifier:@"reuse identifer" configuration:^(id cell) {
        // Configure this cell with data, same as what you've done in "-tableView:cellForRowAtIndexPath:"
        // Like:
        //    cell.entity = self.feedEntities[indexPath.row];
    }];
}

Height Caching API

Since iOS8, -tableView:heightForRowAtIndexPath: will be called more times than we expect, we can feel these extra calculations when scrolling. So we provide another API with caches:

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
    return [tableView fd_heightForCellWithIdentifier:@"identifer" cacheByIndexPath:indexPath configuration:^(id cell) {
        // configurations
    }];
}

Auto cache invalidation

Extra calculations will be saved if a height at an index path has been cached, besides, NO NEED to worry about invalidating cached heights when data source changes, it will be done automatically when you call "-reloadData" or any method that triggers UITableView's reloading.

Precache

Pre-cache is an advanced function which helps to cache the rest of offscreen UITableViewCells automatically, just in "idle" time. It helps to improve scroll performance, because no extra height calculating will be used when scrolls. It's enabled by default if you use "fd_heightForCellWithIdentifier:cacheByIndexPath:configuation:" API.

About estimatedRowHeight

estimatedRowHeight helps to delay all cells' height calculation from load time to scroll time. Feel free to set it or not when you're using FDTemplateLayoutCell. If you use "cacheByIndexPath" API, setting this estimatedRowHeight property is a better practice for imporve load time, and it DOES NO LONGER affect scroll performance because of "precache".

self.tableView.estimatedRowHeight = 200;

Debug log

Debug log helps to debug or inspect what is this "FDTemplateLayoutCell" extention doing, turning on to print logs when "calculating", "precaching" or "hitting cache".Default to "NO", log by "NSLog".

self.tableView.fd_debugLogEnabled = YES;

It will print like this:

** FDTemplateLayoutCell ** layout cell created - FDFeedCell
** FDTemplateLayoutCell ** calculate - [0:0] 233.5
** FDTemplateLayoutCell ** calculate - [0:1] 155.5
** FDTemplateLayoutCell ** calculate - [0:2] 258
** FDTemplateLayoutCell ** calculate - [0:3] 284
** FDTemplateLayoutCell ** precached - [0:3] 284
** FDTemplateLayoutCell ** calculate - [0:4] 278.5
** FDTemplateLayoutCell ** precached - [0:4] 278.5
** FDTemplateLayoutCell ** hit cache - [0:3] 284
** FDTemplateLayoutCell ** hit cache - [0:4] 278.5
** FDTemplateLayoutCell ** hit cache - [0:5] 156
** FDTemplateLayoutCell ** hit cache - [0:6] 165

About self-satisfied cell

a fully self-satisfied cell is constrainted by auto layout and each edge("top", "left", "bottom", "right") has at least one layout constraint against it.

A bad one :( - missing right and bottom

A good one :)

如果你在天朝

可以看这篇中文博客： http://blog.sunnyxx.com/2015/05/17/cell-height-calculation/

Installation

pod search UITableView+FDTemplateLayoutCell 

License

MIT