如何在不使用ARC的情况下管理循环内存？

Question

我正在使用for循环获取十六进制值和NSDATA的ascii值，因为我创建了一个循环。这适用于文件较小的文件，但是当我在大文件上测试时，它的系统会挂起。原因是挂起这个循环消耗所有内存。我试用这个代码与ARC启用或禁用两者是相同的。我也使用@autoreleasepool {块，但没有任何变化。这是我的代码

@autoreleasepool {
    int indexNo = 0000;
    NSMutableString *sbuf = nsData;
    NSInteger ivalue = [sbuf length]/48;
    NSLog(@"%lu",ivalue);



    int j=0;
    for (int i = 0; i <= [sbuf length]/48; i++) {

        NSString *ch;
        NSInteger a =[sbuf length]-j;

        // code here
        if(a < 48){
            ch = [sbuf substringWithRange:NSMakeRange(j,a)];
        }
        else
        {
            ch = [sbuf substringWithRange:NSMakeRange(j,48)];
        }
        NSMutableString * newString = [NSMutableString string];
        NSArray * components = [ch componentsSeparatedByString:@" "];

        for ( NSString * component in components )
        {
            int value = 0;
            sscanf([component cStringUsingEncoding:NSASCIIStringEncoding], "%x", &value);
            [newString appendFormat:@"%c", (char)value];
            // NSLog(@"asckii %c",(char)value);
        }
        //NSLog(@"hexa demp:%@",ch);
        //NSLog(@"ascii Value:%@",newString);
        NSString * stringaxcii = [NSString stringWithString: newString];
        stringaxcii = [[stringaxcii componentsSeparatedByCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] componentsJoinedByString:@"."];
        stringaxcii = [[stringaxcii componentsSeparatedByCharactersInSet:[NSCharacterSet symbolCharacterSet]] componentsJoinedByString:@"."];
        stringaxcii = [[stringaxcii componentsSeparatedByCharactersInSet:[NSCharacterSet controlCharacterSet]] componentsJoinedByString:@"."];
        stringaxcii = [[stringaxcii componentsSeparatedByCharactersInSet:[NSCharacterSet decomposableCharacterSet]] componentsJoinedByString:@"."];
        stringaxcii = [[stringaxcii componentsSeparatedByCharactersInSet:[NSCharacterSet punctuationCharacterSet]] componentsJoinedByString:@"."];


        [self.HexaArray addObject:ch];

        [self.AsciiValue addObject:stringaxcii];

        NSString *hex = [NSString stringWithFormat:@"%08lX",(unsigned long)indexNo];
        indexNo = indexNo+16;

        [self.IndexArray addObject:hex];
        j=j+48;
        if (i ==25) {
            [self.TableView reloadData];

        }
    }

    [self.TableView reloadData];
}