史上最简洁的UITableView Sections 展示包含NSDicionary 的NSArray

这个最典型的就是电话本，然后根据A－Z分组, 当然很多例子，不过现在发现一个很简洁易懂的：

1. 准备数据，定义一个dictionary来显示所有的内容，这个dictionary对应的value全是数组

也就是：

A －> A1, A2... 

B  -> B1, B2...

...

NSMutableDictionary *sections;

2. 创建所有的Keys

BOOL found;
    // Loop through the books and create our keys
    for (NSDictionary *book in self.books) //self.books 就是包含NSDictionary的数组
    {
        NSString *c = [[book objectForKey:@"title"] substringToIndex:1];
 
        found = NO;
 
        for (NSString *str in [self.sections allKeys])
        {
            if ([str isEqualToString:c])
            {
                found = YES;
            }
        }
 
        if (!found)
        {
            [self.sections setValue:[[NSMutableArray alloc] init] forKey:c];
        }
    }

 3. 把Key对应的空数组填满，这个很简单应该能看懂

for (NSDictionary *book in self.books)
    {
        [[self.sections objectForKey:[[book objectForKey:@"title"] substringToIndex:1]] addObject:book];
    }

 4. 下面就排序

for (NSString *key in [self.sections allKeys])
    {
        [[self.sections objectForKey:key] sortUsingDescriptors:[NSArray arrayWithObject:[NSSortDescriptor sortDescriptorWithKey:@"title" ascending:YES]]];
    }

5. 有了上面的方法之后，就执行UITableView必须的方法

#pragma mark -
#pragma mark Table view data source
 
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    return [[self.sections allKeys] count];
}
 
- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section
{
    return [[[self.sections allKeys] sortedArrayUsingSelector:@selector(localizedCaseInsensitiveCompare:)] objectAtIndex:section];
}
 
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return [[self.sections valueForKey:[[[self.sections allKeys] sortedArrayUsingSelector:@selector(localizedCaseInsensitiveCompare:)] objectAtIndex:section]] count];
}
 
- (NSArray *)sectionIndexTitlesForTableView:(UITableView *)tableView {
    return [[self.sections allKeys] sortedArrayUsingSelector:@selector(localizedCaseInsensitiveCompare:)];
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
 
    static NSString *CellIdentifier = @"Cell";
 
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) {
        cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier] autorelease];
    }
 
    NSDictionary *book = [[self.sections valueForKey:[[[self.sections allKeys] sortedArrayUsingSelector:@selector(localizedCaseInsensitiveCompare:)] objectAtIndex:indexPath.section]] objectAtIndex:indexPath.row];
 
    cell.textLabel.text = [book objectForKey:@"title"];
    cell.detailTextLabel.text = [book objectForKey:@"description"];
 
    return cell;
}

 差不多了，这个是我见过最简洁的例子了。

参考：http://www.icodeblog.com/2010/12/10/implementing-uitableview-sections-from-an-nsarray-of-nsdictionary-objects/