iphone - if else 条件不能正常工作总是运行 else

Question

我正在使用 if else 条件来检查变量，但是当 value 为 true 时它也总是运行 else 然后它也显示 else

NSString *data=[[NSString alloc]initWithData:urlData encoding:NSUTF8StringEncoding];
NSLog(@"%@",data);

if ([data isEqualToString:@"Yes"]) {

    UIAlertView * alert = [[UIAlertView alloc] initWithTitle:@"Welcome" message:@"Successful Login" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
    [alert show];
    [alert release];

}  
else {
    UIAlertView * alert = [[UIAlertView alloc] initWithTitle:@"Error" message:@"Incorrect user name or password" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
    [alert show];
    [alert release];

}

Answer 1

试试这个代码，

 NSString *data=[[NSString alloc]initWithData:urlData encoding:NSUTF8StringEncoding];
    data = [data stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
    NSLog(@"%@",data);

    if ([data caseInsensitiveCompare:@"Yes"] == NSOrderedSame) {

        UIAlertView * alert = [[UIAlertView alloc] initWithTitle:@"Welcome" message:@"Successful Login" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
        [alert show];
        [alert release];

    }
    else {
        UIAlertView * alert = [[UIAlertView alloc] initWithTitle:@"Error" message:@"Incorrect user name or password" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
        [alert show];
        [alert release];

    }

Answer 2

将此用作：

 if ([[data stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] isEqualToString:@"Yes"]) 
{

}

编辑：您的代码运行良好，因为我在最后检查了它。

希望它可以帮助你。