OC-NSString中，写了一个在母串中查找子串的位置，但是检索的信息有遗漏，请问是哪儿出现了问题？

Question

    NSString * motherstr = @"w is w is w";
    NSString * sonstr = @"w";
    NSRange range = [motherstr rangeOfString:sonstr];
    while(range.location != NSNotFound)
    {
        NSLog(@"start = %@",NSStringFromRange(range));
        NSRange temp = NSMakeRange((range.location + range.length), (motherstr.length-(range.location+range.length)));
        range =[motherstr rangeOfString:sonstr options:NSBackwardsSearch range:temp];
    }

查找的时候只找到了开头和结尾中的w,中间的包含的子串字符并没有找到，想了很久也没想出来为什么，求大神告知。

Answer 1

NSString * motherstr = @"a is a , so a not equal b";
NSString * sonstr = @"a";
NSRange range = [motherstr rangeOfString:sonstr options:NSBackwardsSearch range:NSMakeRange(0, motherstr.length)];
//循环检索
while(range.location != NSNotFound)
{
NSLog(@"start = %@",NSStringFromRange(range));
NSUInteger start = 0;
NSUInteger end = range.location;
NSRange temp = NSMakeRange(start,end);
range =[motherstr rangeOfString:sonstr options:NSBackwardsSearch range:temp];
}
总算解决了，写的不咋滴，希望大家赐教...