我读过创建索引（uitableview 旁边的 a-z）的最佳方法是设置一个 nsdictionaries 数组，其中每个字典对应一个部分，并且 rowValue 键包含一个数组行。
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数组中创建它 - {”Aardvark”、“Ape”、“Aquaman”、“Bat”、“Boot”、“Bubbles”、“Cat”、“Cabbage”等等} ...？
【问题讨论】：
标签： objective-c ios uitableview nsarray nsdictionary
我最近有一个类似的目标，这就是我解决它的方法。与 Robin 的解决方案相比，它的优势在于它会根据数组的内容动态创建索引标题数组，并且不会包含空白部分的索引（而且它更简洁一些）。
我创建了一个NSMutableDictionary 类别，它接受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];
分类方法：
@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indexDictionary 的所有键：
// this line should follow the creation of `indexDictionary`
sortedKeys = [[indexDictionary allKeys] sortedArrayUsingSelector:@selector(localizedCaseInsensitiveCompare:)];
// Output, in this case, is {'A', 'B', 'C', 'E'}
您现在拥有为表设置索引所需的一切。实现以下方法（如果有些东西不能自我解释，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，该索引会跳过没有关联数据的字母。
【讨论】：
name beginswith[cd] %@而不是SELF beginswith[cd] %@。这将按每个字典的名称字段对您的字典数组进行排序。
#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。
【讨论】：
我正在做一个项目，我需要针对同一问题的动态解决方案，所以我想出了这个解决方案，它只返回包含可用部分的字典。希望对某人有所帮助。
-(NSMutableDictionary *)getSortedDataWithArray:(NSArray *)dataArray{
NSMutableDictionary *allDataDictionary = [[NSMutableDictionary alloc]init];
for(int i = 0 ; i< dataArray.count ;i++){
NSString *currentStr = [[[dataArray objectAtIndex:i] substringToIndex:1] uppercaseString];
NSArray *allKeysArray = allDataDictionary.allKeys;
if([allKeysArray containsObject:currentStr]){
NSMutableArray *currentArray = [[NSMutableArray alloc] initWithArray:[allDataDictionary valueForKey:currentStr]];
[currentArray addObject:[dataArray objectAtIndex:i]];
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF beginswith[c] %@" ,currentStr];
NSArray *finalArray = [currentArray filteredArrayUsingPredicate:predicate];
[allDataDictionary setValue:finalArray forKey:currentStr];
}
else{
NSMutableArray *finalArray = [[NSMutableArray alloc] initWithObjects:[dataArray objectAtIndex:i], nil];
[allDataDictionary setValue:finalArray forKey:currentStr];
}
}
return allDataDictionary;
}
【讨论】：