Objective-C iPhone 编程：尝试捕获异常

发布于 2024-10-25 22:39:31 字数 257 浏览 14 评论 0原文

我使用 kumulos 来访问数据库。这是我正在谈论的代码：

NSString *location = [[theResults objectAtIndex:0] objectForKey:@"location"];

现在如果 [theResults objectatindex:0] 返回“null”，它每次都会崩溃因此，如果用户输入数据库中没有的内容，则会崩溃，我想捕获此异常（NSRange 异常）。

谢谢

原文

im using kumulos to have access to a database.
this is the code i am talking about :

NSString *location = [[theResults objectAtIndex:0] objectForKey:@"location"];

Now the thing if [theResults objectatindex:0] return "null" it crash everytime
so if the user enter something that is not in the database it crash i want to catch this exeption (NSRange exeception).

Thanks

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又爬满兰若 2024-11-01 22:39:31

我认为这对你有用，不需要异常处理。

if ([theResults count] > 0) {
    NSString *location = [[theResults objectAtIndex:0] objectForKey:@"location"];
}

我假设 theResults 是一个 NSArray （或子类）。

I think this will work for you without requiring exception handling.

if ([theResults count] > 0) {
    NSString *location = [[theResults objectAtIndex:0] objectForKey:@"location"];
}

I'm assuming that theResults is an NSArray (or subclass).

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我只土不豪 2024-11-01 22:39:31

要么检查 [theResults objectAtIndex:0] 不返回 nil，要么使用异常处理，但

@try {
   NSString *location = [[theResults objectAtIndex:0] objectForKey:@"location"];  
}
@catch (NSRangeEception * e) {
   NSLog(@"catching %@ reason %@", [e name], [e reason]);
}
@finally {
   //something that you want to do wether the exception is thrown or not.
}

我建议至少学习一下该语言，或者使用 google 进行练习:-)

either you check that [theResults objectAtIndex:0] does not return nil, or you use exception handling

@try {
   NSString *location = [[theResults objectAtIndex:0] objectForKey:@"location"];  
}
@catch (NSRangeEception * e) {
   NSLog(@"catching %@ reason %@", [e name], [e reason]);
}
@finally {
   //something that you want to do wether the exception is thrown or not.
}

I would suggest to study the language at least a little bit, though, or practice with google :-)

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