Question

我有这段代码，（我没写过）：

- (BOOL)execute:(NSString *)sqlCommand error:(NSError **)error
{
    const char *sql = [sqlCommand UTF8String];
    char *errorPointer;
    if (sqlite3_exec(database, sql, NULL, NULL, &errorPointer) != SQLITE_OK)
    {
        if (error)
        {
            NSString *errMsg = [NSString stringWithCString:errorPointer encoding:NSUTF8StringEncoding];
            NSString *description = @"An error occurred executing the SQL statement";
            NSDictionary *userInfo = [NSDictionary dictionaryWithObjectsAndKeys:description, NSLocalizedDescriptionKey, errMsg, NSLocalizedFailureReasonErrorKey, nil];
            *error = [[[NSError alloc] initWithDomain:SQLCipherManagerErrorDomain code:ERR_SQLCIPHER_COMMAND_FAILED userInfo:userInfo] autorelease];
            sqlite3_free(error);
        }
        return NO;
    }
    return YES;
}

我也有一个没有“error”参数的方法，我会用这样的方法调用：[dm execute：insertCommand];

我的问题是：我将使用带有“error”参数的方法调用的格式是什么，所以我可以看到来自调用的任何错误？

Answer 1

像那样：

NSError* error = nil;
BOOL success = [dm execute:insertCommand error:&error];

if (success == NO)
{
  // do whatever if failed
}

另见cocoa文档中的"Handling Error Objects Returned From Methods"。

Answer 2

NSError *error = nil; //your error
if(![dm execute:sqlCommand error:&error])
{ //Pass the address to your pointer ^^

    //Since you passed the address of your error pointer
    //your execute command was able to set it to an
    //NSError if one occurrs
}

Answer 3

您必须在代码调用之外声明一个NSError对象，并传入地址：

NSError *error;
BOOL success = [whateverObj execute:theSqlStmt error:&error];
if (!success) {
    // Handle error
}

调用此代码的格式是什么？

3 个答案: