我正在研究使用 Objective-C 实现主题标签自动完成,如图所示
我发现它比预期的要难一些。我正在寻找用于添加和删除主题标签的更具体的实现。例如,应立即删除主题标签。我想知道是否有人有类似的实现经验,以及是否有更有效的实现方法。谢谢
最佳答案
我最终写了一些我觉得有点难看但有效的函数。也许有一些更有效的方法来实现它。
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
//user is a singleton instance
User *user = [User sharedUser];
user.autocompleteTableView.hidden = NO;
int identifiedTagsStringLength = [self.identifiedTagsString length];
int cursorLocation = range.location;
//insert characters
if (range.location >= identifiedTagsStringLength) {
NSString *newSearch =@"";
NSRange newRange;
if(identifiedTagsStringLength != 0) {
newSearch = [urlField.text substringFromIndex:identifiedTagsStringLength];
newRange = NSMakeRange(range.location - identifiedTagsStringLength, 0);
}
else {
newSearch = textField.text;
newRange = range;
}
NSString *substring = [NSString stringWithString:newSearch];
substring = [substring stringByReplacingCharactersInRange:newRange withString:string];
[self searchAutocompleteEntriesWithSubstring:substring];
if (cursorLocation > currentTagsRange) {
currentTagsRange = cursorLocation;
}
}
//delete tags
else {
if ([self.ranges count] != 0 && cursorLocation < currentTagsRange) {
int rangeLength = [self.ranges count];
int toBeRemovedIndex = 0;
for (int i = 0; i< rangeLength; i++) {
if (cursorLocation >= [[self.ranges objectAtIndex:i][0] intValue]
&& cursorLocation <= [[self.ranges objectAtIndex:i][1] intValue]) {
toBeRemovedIndex = i;
}
}
[self.tags removeObjectAtIndex:toBeRemovedIndex];
[self updateRanges];
NSString *outputString = @"";
for (NSString *tag in self.tags) {
outputString = [NSString stringWithFormat:@"%@#%@ ", outputString,
tag];
}
urlField.text = outputString;
self.identifiedTagsString = urlField.text;
currentTagsRange = [outputString length] - 1;
}
}
return YES;
}
- (void)updateRanges {
self.ranges = [[NSMutableArray alloc] init];
int startIndex = 0;
for (NSString *tag in self.tags) {
startIndex = [self.ranges count] == 0 ? 0 : [[self.ranges lastObject][1] intValue] + 1;
int tagLength = [tag length];
NSArray *range = [NSArray arrayWithObjects:[NSNumber numberWithInt:startIndex], [NSNumber numberWithInt:startIndex + tagLength + 1], nil];
[self.ranges addObject: range];
}
}
#pragma mark UITableViewDataSource methods
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
UITableViewCell *selectedCell = [tableView cellForRowAtIndexPath:indexPath];
if (self.identifiedTagsString == NULL) {
self.identifiedTagsString = @"";
}
[self.tags addObject: selectedCell.textLabel.text];
[self updateRanges];
NSString *output = @"";
for (NSString *tag in self.tags) {
output = [NSString stringWithFormat:@"%@#%@ ", output, tag];
}
urlField.text = output;
User *user = [User sharedUser];
user.autocompleteTableView.hidden = YES;
self.identifiedTagsString = urlField.text;
currentTagsRange = [urlField.text length];
}
关于ios - Objective-C 主题标签/标签自动完成实现,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/22886688/