最后发现需要6.0以后，因为nsfontattributename之类的是6.0以后的api

    长久以来，我以为富文本是一种在ios中使用特别麻烦的事情，但是不经意的研究发现，其实并没有那么难！

   以下的代码实现了uilabel中放置富文本。

NSMutableAttributedString *richTask = [[NSMutableAttributedString alloc] initWithString:task];NSDictionary *urgentAttributes = @{NSFontAttributeName : [UIFont fontWithName:@"Courier" size:24],NSStrokeWidthAttributeName : @3.0,NSStrokeColorAttributeName:[UIColor greenColor]};[richTask setAttributes:urgentAttributes range:urgentRange];

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{NSString *identifier = nil;NSString *task = [self.tasks objectAtIndex:indexPath.row];NSRange urgentRange = [task rangeOfString:@"URGENT"];if (urgentRange.location == NSNotFound) {identifier = @"plainCell";} else {identifier = @"attentionCell";}UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:identifier];// Configure the cell...UILabel *cellLabel = (UILabel *)[cell viewWithTag:1];NSMutableAttributedString *richTask = [[NSMutableAttributedString alloc] initWithString:task];NSDictionary *urgentAttributes = @{NSFontAttributeName : [UIFont fontWithName:@"Courier" size:24],NSStrokeWidthAttributeName : @3.0,NSStrokeColorAttributeName:[UIColor greenColor]};[richTask setAttributes:urgentAttributes range:urgentRange];if (urgentRange.location != NSNotFound) {NSRange otherPartRange = NSMakeRange(urgentRange.length+urgentRange.location, task.length-urgentRange.length);NSDictionary* otherPartAttributes = @{NSFontAttributeName : [UIFont fontWithName:@"Courier" size:12],NSStrokeWidthAttributeName : @0,NSStrokeColorAttributeName:[UIColor redColor]};[richTask setAttributes:otherPartAttributes range:otherPartRange];}cellLabel.attributedText = richTask;return cell;
}