ios - 为给定字符串的所有字符突出显示字符串中的特定字符

Question

标签上的特定字符要以红色突出显示，所以我在下面写了一个很好用的函数，但我想确认一下，还有其他有效的方法吗？例如

-(NSMutableAttributedString*)getAttributeText:(NSString*)string forSubstring:(NSString*)searchstring {
    NSMutableAttributedString *text = [[NSMutableAttributedString alloc] initWithString:_lblName.text];
    NSRange searchRange = NSMakeRange(0,string.length);
    for (NSInteger charIdx=0; charIdx<searchstring.length; charIdx++){
        NSString *substring = [searchstring substringWithRange:NSMakeRange(charIdx, 1)];
        NSRange foundRange;
        searchRange.location = 0;
        while (searchRange.location < string.length) {
            searchRange.length = string.length-searchRange.location;
            foundRange = [string rangeOfString:substring options:1 range:searchRange];
            [text addAttribute: NSForegroundColorAttributeName value: [UIColor redColor] range:foundRange];
            if (foundRange.location != NSNotFound) {
                searchRange.location = foundRange.location+foundRange.length;
            } else {
                // no more substring to find
                break;
            }
        }
    }
    return text;
}

下面是我如何使用它的代码，以及结果

NSString *string = @"James Bond Always Rocks";
_lblName.text = string;
_lblAttributedName.attributedText = [self getAttributeText:string forSubstring:@"ao"];

更新

NSString *string = @"James Bond Always Rocks";    
NSRange range = [string rangeOfCharacterFromSet:[NSCharacterSet characterSetWithCharactersInString:@"J"] options:NSCaseInsensitiveSearch];
NSLog(@"range->%@",NSStringFromRange(range)); //This prints range->{0, 1}

NSString *string = @"James Bond Always Rocks";    
NSRange range = [string rangeOfCharacterFromSet:[NSCharacterSet characterSetWithCharactersInString:@"j"] options:NSCaseInsensitiveSearch];
NSLog(@"range->%@",NSStringFromRange(range)); //This prints range->{2147483647, 0}

Answer 1

您可以通过搜索模式(在您的示例中为“[ao]+”)来简化它以消除 外循环:

NSString *string = @"James Bond Always Rocks";
NSString *searchstring = @"ao";
NSMutableAttributedString *text = [[NSMutableAttributedString alloc] initWithString:string];

// A regular expression pattern that matches a sequence of the characters in "searchString":
NSString *pattern = [NSString stringWithFormat:@"[%@]+", [NSRegularExpression escapedPatternForString:searchstring]];

NSRange foundRange = [string rangeOfString:pattern options:NSRegularExpressionSearch|NSCaseInsensitiveSearch];
while (foundRange.location != NSNotFound) {
    [text addAttribute: NSForegroundColorAttributeName value: [UIColor redColor] range:foundRange];
    NSRange nextRange = NSMakeRange(foundRange.location + foundRange.length, string.length - foundRange.location - foundRange.length);
    foundRange = [string rangeOfString:pattern options:NSRegularExpressionSearch|NSCaseInsensitiveSearch range:nextRange];
}