xCode 4.2错误

Question

尝试加载其他视图时出现此错误：

2012-02-21 20:31:38.477 App Demo[1671:f803] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[NSPlaceholderString initWithString:]: nil argument'

我找不到错误的确切位置。

有什么帮助吗？

更新

NSString *pn1 = player1name.text;
NSString *pn2 = player2name.text;
NSString *pn3 = player3name.text;
NSString *pn4 = player4name.text;
NSString *k = kingdomLevel.text;

Kscores *kscores = [[Kscores alloc] initWithNibName:nil bundle:nil];
kscores.modalTransitionStyle = UIModalTransitionStyleFlipHorizontal;
[self presentModalViewController:kscores animated:YES];


[[kscores player1name] setText:[NSString stringWithString:(NSString *)pn1]];
[[kscores player2name] setText:[NSString stringWithString:(NSString *)pn2]];
[[kscores player3name] setText:[NSString stringWithString:(NSString *)pn3]];
[[kscores player4name] setText:[NSString stringWithString:(NSString *)pn4]];
[[kscores king] setText:[NSString stringWithString:(NSString *)k]];

断点在此代码处停止

[[kscores player1name] setText:[NSString stringWithString:(NSString *)pn1]];

Answer 1

做stringWithString:有什么stringWithString: ？ 您可以像[[kscores player1name] setText:pn1];一样直接设置它[[kscores player1name] setText:pn1];

因为pn1为nil，所以无法收到错误，并且无法将nil传递给stringWithString:

Answer 2

这意味着pn1为nil ：

[[kscores player1name] setText:[NSString stringWithString:(NSString *)pn1]];

这意味着player1name或player1name.text在该行中为nil ：

NSString *pn1 = player1name.text;

Answer 3

您正在尝试传递nil参数： [[kscores player1name] setText:nil]; 由于[NSString stringWithString:(NSString *)pn1]为NULL 。

相反，请尝试以下操作： [[kscores player1name] setText: pn1]