IOS7笔记-６、控制器多态性、导航控制器、选项卡栏控制器

１、遍历符合条件字符

 1 -(NSAttributedString *)charactersWithAttribute:(NSString *)attributeName
 2 {
 3     NSMutableAttributedString *characters = [[NSMutableAttributedString alloc] init];
 4
 5     int index = 0;
 6     while (index < [self.textToAnalyze length]) {
 7         NSRange range;
 8         id value = [self.textToAnalyze attribute:attributeName
 9                                          atIndex:index
10                                   effectiveRange:&range];
11         if (value) {
12             [characters appendAttributedString:[self.textToAnalyze attributedSubstringFromRange:range]];
13             index = range.location + range.length;
14         } else {
15             index++;
16         }
17     }
18
19     return characters;
20 }

1 -(void)updateUI
2 {
3     self.colorfulCharactersLabel.text = [NSString stringWithFormat:@"%d colorful characters", [[self charactersWithAttribute:NSForegroundColorAttributeName] length]];
4     self.outlinedCharactersLabel.text = [NSString stringWithFormat:@"%d outlined characters", [[self charactersWithAttribute:NSStrokeWidthAttributeName] length]];
5 }

２、segue识别代码

1 -(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
2 {
3     if ([segue.identifier isEqualToString:@"Analyze Text"]) {
4         if ([segue.destinationViewController isKindOfClass:[TextStatsViewController class]]) {
5             TextStatsViewController *tsvc = (TextStatsViewController *)segue.destinationViewController;
6             tsvc.textToAnalyze = self.body.textStorage;
7         }
8     }
9 }