XCODE从文件中读取文本会删除变量

这可能是我见过的最奇怪的错误。 我正在创建一个迷宫游戏，从文本文件加载关卡，但如果文件有三行以上，它似乎会随机更改我的大多数变量。我加载一个文本文件，然后遍历这些行，并根据其字母在适当的位置创建一个对象。 有什么建议吗

文本文件： TTTTTTTTTTTTTTTTTTT TTTTTTTTTTTTTTTTTTT TTTTTTTTTTTTTTTTTTT TTTTT RPPGPPDTTTTT ttttptptttt TTTTPPPWPPTTTTT ttttptppptttt ttttppptptttt ttttptppptttt ttttt upppplttt TTTTTTTTTTTTTTTTTT TTTTTTTTTTTTTTTTTTT TTTTTTTTTTTTTTTTTT

NSString *path = [[NSBundle mainBundle] pathForResource:@"map2c" ofType:@"txt"];
NSString *contents = [NSString stringWithContentsOfFile:path encoding:NSASCIIStringEncoding error:nil];
NSArray *lines = [contents componentsSeparatedByCharactersInSet:[NSCharacterSet characterSetWithCharactersInString:@"\r\n"]];
int y  = 0;
for (NSString* line in lines) {

    NSString* ty = @"TBGWUDLRP";
    char *str = (char *)[line UTF8String];
    char *str2 = (char*)[ty UTF8String];
    grannyMoving = 2;
    int x = str2[0];
    char x2 = str2[1];
    char GrannyStr = str2[2];
    char wolfStr = str2[3];

    char UpStr = str2[4];
    char DownStr = str2[5];
    char leftStr = str2[6];
    char rightStr = str2[7];
    char PathStr = str2[8];
    y--;
    maxY = y;
    if (line.length) {
        maxI = line.length;
        for (int i = 0; i< line.length; i++) {                
 SKSpriteNode* tree = [SKSpriteNode spriteNodeWithImageNamed:@"tree3"];
            tree.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:CGSizeMake(31, 31)];
            tree.physicsBody.affectedByGravity = false;
            tree.physicsBody.dynamic = NO;
            tree.position = CGPointMake(64*i+20, 64*y+800);
            tree.zPosition = -1* tree.position.y;

从：

此C字符串是指向string对象内部结构的指针， 它的生存期可能比字符串对象短，并且将 当然不会有更长的寿命。因此，您应该复制C 字符串，如果它需要存储在 您可以使用此属性

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要解决此问题，必须复制UTF8String返回的字符。提供两种解决方案。

重置的变量不仅仅是这些变量，甚至是在此之前设置的属性，包括SKActionsASO获取我分配的变量的exc\u bad\u访问权限