Question

我无法弄清楚为什么这段代码很糟糕。我认为在dictionaryWithObjectsAndKeys中使用静态字符串是可以的，但它在运行时因EXC_BAD_ACCESS而失败。我使用调试器来识别它在定义行中实际上是失败的。它永远不会输出“Made it here”。

- (NSString *)polyName:(NSUInteger)vertices { 
    NSLog(@"looking for polyName with %d vertices.", vertices);

    NSDictionary *polNameDict = [NSDictionary dictionaryWithObjectsAndKeys:
                             @"triangle", @"3", 
                             @"square", @"4",
                             @"pentagon","5",
                             @"Hexagon", @"6",
                             @"Heptagon", @"7",
                             @"Octagon", @"8",
                             @"Nonagon", @"9",
                             @"Decagon", @"10",
                             @"Hendecagon", @"11",
                             @"Dodecagon", @"12",
                             nil];

   NSLog(@"Made it here");

   NSString *key = [NSString stringWithFormat: @"%d", vertices]; 
   NSString *polName = [polNameDict objectForKey:key];
   return (polName);
   // Memory management: No need to release polNameDict, key, polName because they use
   // convenience functions
}

Answer 1

问题在于：

@"pentagon","5"

它需要一个对象（NSString），而是有一个常规字符串将其更改为：

@"pentagon", @"5"

Answer 2

EXC_BAD_ACCESS出现在哪一行？利用断点告诉我们。

现在，如果我是你，我会做这样的事情：

NSDictionary *polNameDict = [[NSDictionary alloc] initWithObjectsAndKeys:
                             @"triangle", @"3", 
                             @"square", @"4",
                             @"pentagon",@"5",
                             @"Hexagon", @"6",
                             @"Heptagon", @"7",
                             @"Octagon", @"8",
                             @"Nonagon", @"9",
                             @"Decagon", @"10",
                             @"Hendecagon", @"11",
                             @"Dodecagon", @"12",
                             nil];

而不是现在的方式。

NSDictionary初始化导致“EXC_BAD_ACCESS”

2 个答案: