当我点击“保存”时,我在回到AppDelegate时遇到错误。
我敢肯定,我在这里缺少一些小东西,但如果有人有快速回答,我将不胜感激。
这是我得到的错误:
-[AppDelegate saveNewUsername:username:]: unrecognized selector sent to instance 0x8e403d0
这是我的按钮操作:
-(IBAction)saveButtonPressed:(id)sender
{
AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
NSString *userid = [appDelegate retrieveFromUserDefaults:@"userid"];
NSMutableArray *currentUser = [appDelegate getUserInfo:userid];
NSString *currentUsername = [currentUser objectAtIndex:0];
NSLog(@"%@", userid);
if ([currUsername.text isEqualToString:currentUsername]) {
//here we'll check and make sure the new username is valid and doesn't already exist (for now just update local DB)
if ([theNewUsername.text isEqualToString:@""]) {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"" message:@"You must enter something for your new username." delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];
[alert show];
} else {
int returnVal = [appDelegate saveNewUsername:userid username:theNewUsername.text];
if (returnVal == 1) {
[self dismissModalViewControllerAnimated:YES];
} else {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Error" message:@"There was an error saving to the database." delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];
[alert show];
}
}
} else {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"" message:@"The username you entered is not your current username." delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];
[alert show];
}
}
这是我的AppDelegate方法:
-(int)saveNewUsername:(NSString *)user_id username:(NSString *)username
{
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *writableDBPath = [documentsDirectory stringByAppendingPathComponent:@"somedbname.sqlite3"];
FMDatabase *db = [FMDatabase databaseWithPath:writableDBPath];
if (![db open]) {
NSLog(@"Could not open db.");
return 0;
} else {
[db intForQuery:@"UPDATE user SET username=? WHERE user_id=?", username, user_id];
if ([db hadError]) {
NSLog(@"Error %d: %@", [db lastErrorCode], [db lastErrorMessage]);
return 0;
} else {
return 1;
}
}
}
答案 0 :(得分:1)
您的代码看起来不错。所以我猜appDelegate实际上不是AppDelegate的实例。
AppDelegate *appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];
在那里设置断点并查看调试器以检查它是否确实是AppDelegate的实例。