从NSArray为UITableView创建索引
我已经读过创建索引（uitableview一侧的az）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，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数组中创建 – {“Aardvark”，“Ape”，“Aquaman”，“Bat”，“Boot”，“Bubbles”，“Cat”，“Cabbage”等}。 ..？
#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。
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NSMutableDictionary类，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indexDictionary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。
我正在开发一个项目，我需要针对同一问题的动态解决方案，所以我找到了这个只返回字段的解决方案。 希望它可以帮到某人。
-(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; }