iOS算法之-找到字符串中第一个不重复的字符

 NSString *str = @"qwrwqrqrqrwqwrql12e1e12ffw";
 NSMutableArray * strArr = [NSMutableArray arrayWithCapacity:0];
// 遍历字符串，按字符来遍历。每个字符将通过block参数中的substring传出
[str enumerateSubstringsInRange:NSMakeRange(0, str.length) options:NSStringEnumerationByComposedCharacterSequences usingBlock:^(NSString *substring, NSRange substringRange, NSRange enclosingRange, BOOL *stop) {
    [strArr addObject:substring];
}];
NSString *m = @"";
int i =0;
do
{
    i = 0;
    m = strArr[0];
    for(int j = 1 ; j < strArr.count; j++)
    {
        if([m isEqualToString:strArr[j]])
        {
            [strArr removeObject:m];
            i = 1;
            break;
        }
    }
}
while( i == 1);
NSLog(@"%@",strArr[0]);