从NSArray为UITableView创建索引

Question

我已经读过创建索引的最佳方法(在uitableview一侧的az)是设置一个nsdictionaries数组,其中每个字典对应一个部分,rowValue键包含一个行数组.

NSDictionary
    headerTitle => ‘A’
    rowValues => {”Aardvark”, “Ape”, “Aquaman”}
NSDictionary
    headerTitle => ‘B’
    rowValues => {”Bat”, “Boot”, “Bubbles”} etc

但是如何从所有行标题的阵列中创建 - {"Aardvark","Ape","Aquaman","Bat","Boot","Bubbles","Cat","Cabbage"等}. ..？

Answer 1

我最近有一个类似的目标,这就是我解决它的方式.这比Robin的解决方案的优势在于它根据数组的内容动态创建索引标题数组,并且它不包括空部分的索引(加上它更清晰一点).

我创建了一个类别NSMutableDictionary,它将一个数据数组作为参数并返回一个NSMutableDictionary(我们称之为indexDictionary它应该是一个实例变量):

// if your data is static, you can call this in `viewDidLoad`
indexDictionary = [NSMutableDictionary createDictionaryForSectionIndex:arrayOfStrings];

类别方法:

@implementation NSMutableDictionary (DictionaryForSectionIndex)

+(NSMutableDictionary *)createDictionaryForSectionIndex:(NSArray *)array
{
    NSMutableDictionary *dict = [NSMutableDictionary dictionary];
    for (char firstChar = 'a'; firstChar <= 'z'; firstChar++)
    {
        //NSPredicates are fast
        NSString *firstCharacter = [NSString stringWithFormat:@"%c", firstChar];
        NSArray *content = [array filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"SELF beginswith[cd] %@", firstCharacter]];
        NSMutableArray *mutableContent = [NSMutableArray arrayWithArray:content];

        if ([mutableContent count] > 0)
        {
            NSString *key = [firstCharacter uppercaseString];
            [dict setObject:mutableContent forKey:key];
            NSLog(@"%@: %u", key, [mutableContent count]);
        }
    }

    return dict;
}

@end

/*

**Input:** 
{"Aardvark", "Cabbage", "Boot", "Eggs", "Ape", "Aquaman", "Elephant", "Cat", "Bat", "Bubbles"}

**Output:**
NSMutableDictionary
    key => 'A'
    object => {"Aardvark", "Ape", "Aquaman"}

    key => 'B'
    object => {"Bat", "Boot", "Bubbles"}

    key => 'C'
    object => {"Cat", "Cabbage"}

    key => 'E'
    object => {"Elephant", "Eggs"}

*/

然后我创建一个NSArray实例变量来排序和存储来自的所有键indexDictionary:

// this line should follow the creation of `indexDictionary`

sortedKeys = [[indexDictionary allKeys] sortedArrayUsingSelector:@selector(localizedCaseInsensitiveCompare:)];

// Output, in this case, is {'A', 'B', 'C', 'E'}

您现在拥有了为表设置索引所需的一切.实现以下方法(如果某些内容不能自我解释,请告诉我):

//this code assumes `sortedKeys` is not empty

#pragma mark - UITableViewDataSource

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    return ([sortedKeys count]);
}


- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    NSString *key = [sortedKeys objectAtIndex:section];
    return [[indexDictionary valueForKey:key] count];
}


-(NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section
{
    return ([sortedKeys objectAtIndex:section]);
}


-(NSArray *)sectionIndexTitlesForTableView:(UITableView *)tableView
{
    return sortedKeys;
}


-(NSInteger)tableView:(UITableView *)tableView sectionForSectionIndexTitle:(NSString *)title atIndex:(NSInteger)index
{
    return index;
}


- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    // preceding code...

    NSString *key = [sortedKeys objectAtIndex:indexPath.section];
    NSArray *array = [indexDictionary objectForKey:key];
    NSString *yourString = [array objectAtIndex:indexPath.row];

    cell.textLabel.text = yourString;

    // following code...
}

结果是一个带有索引的表,该索引跳过没有关联数据的字母.

Answer 2

#pragma mark -
#pragma mark View lifecycle
- (void)viewDidLoad
{
    [super viewDidLoad];
    NSMutableArray *temp = [[NSMutableArray alloc] init];
    NSMutableArray *temp2 = [[NSMutableArray alloc] init];
    for(int i = 0; i < tableListArray.count; i++)
    {
        NSString *string = [tableListArray objectAtIndex:i];
        NSMutableDictionary *dict = [[NSMutableDictionary alloc] init];
        [dict setObject:string forKey:@"Name"];
        [dict setObject:[NSNumber numberWithInt:i] forKey:@"ID"];
        NSString *firstString = [string substringToIndex:1];
        if([temp2 containsObject:firstString] == NO || temp2.count == 0)
        {
            if(temp2.count != 0)
            {
                [temp addObject:temp2];
                [temp2 release];
                temp2 = [[NSMutableArray alloc] init];
            }
            [temp2 addObject:firstString];
        }
        [temp2 addObject:dict];
        [dict release];
    }
    [temp addObject:temp2];
    detailListArray = [[NSArray alloc] initWithArray:temp];
    [temp release];
    [temp2 release];
}

#pragma mark -
#pragma mark Table view data source
- (NSInteger)tableView:(UITableView *)tableView 
sectionForSectionIndexTitle:(NSString *)title atIndex:(NSInteger)index
{
    int i = 0;
    for(NSArray *array in detailListArray)
    {
        NSString *string = [array objectAtIndex:0];
        if([string compare:title] == NSOrderedSame)
            break;
        i++;
    }
    return i;
}

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    return detailListArray.count;
}

- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section
{
    NSArray *array = [detailListArray objectAtIndex:section];
    return [array objectAtIndex:0];
}

- (NSArray *)sectionIndexTitlesForTableView:(UITableView *)tableView 
{
    NSMutableArray *titleArray = [NSMutableArray array];
    [titleArray addObject:@"A"];
    [titleArray addObject:@"B"];
    [titleArray addObject:@"C"];
    [titleArray addObject:@"D"];
    [titleArray addObject:@"E"];
    [titleArray addObject:@"F"];
    [titleArray addObject:@"G"];
    [titleArray addObject:@"H"];
    [titleArray addObject:@"I"];
    [titleArray addObject:@"J"];
    [titleArray addObject:@"K"];
    [titleArray addObject:@"L"];
    [titleArray addObject:@"M"];
    [titleArray addObject:@"N"];
    [titleArray addObject:@"O"];
    [titleArray addObject:@"P"];
    [titleArray addObject:@"Q"];
    [titleArray addObject:@"R"];
    [titleArray addObject:@"S"];
    [titleArray addObject:@"T"];
    [titleArray addObject:@"U"];
    [titleArray addObject:@"V"];
    [titleArray addObject:@"W"];
    [titleArray addObject:@"X"];
    [titleArray addObject:@"Y"];
    [titleArray addObject:@"Z"];
    return titleArray;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    NSArray *array = [detailListArray objectAtIndex:section];
    return (array.count - 1);
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell *cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault
                                                    reuseIdentifier:@"CELL"] autorelease];
    NSArray *array = [detailListArray objectAtIndex:indexPath.section];
    NSDictionary *dict = [array objectAtIndex:indexPath.row + 1];
    cell.textLabel.text = [dict objectForKey:@"Name"];
    return cell;
}

#pragma mark -
#pragma mark Table view delegate
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    NSArray *array = [detailListArray objectAtIndex:indexPath.section];
    NSDictionary *dict = [array objectAtIndex:indexPath.row + 1];
    int entryID = [[dict objectForKey:@"ID"] intValue];
     // Do what ever you want to do with the selected row here....
}

这是我在最近的一个项目中使用的代码.