//查找某关键字在目标字符串中出现次数及位置- (NSMutableArray *)filterString{    NSString *str = @"abcdefg&123_我们haha,.123hf 123";    NSLog(@"%lu~~%i",strlen((char *)[str UTF8String]),[str length]);    NSRange range={
   0,0};    NSMutableArray *arr = [[NSMutableArray alloc]initWithCapacity:0];    //每次指针偏移量    int loc = 0;    while (range.location<[str length])     {        loc += range.location+range.length;        str = [str substringFromIndex:(range.location+range.length)];        NSLog(@"%@",str);        range = [str rangeOfString:@"123"];        if(range.location==NSNotFound)            break;        [arr addObject:[NSNumber numberWithInt:(loc+range.location)]];        NSLog(@"%i,%i",loc+range.location,range.length);    }    return [arr autorelease];}