iOS:简化 UIAlertView 代码以便可以反复使用

Question

这是我学习 XCode 的第二天，所以我在这里完全是新手，我有这个 .m 代码:​​

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
    [_fieldEmail setFont:[UIFont fontWithName:@"ABeeZee-Regular" size:14]];
    [_fieldPassword setFont:[UIFont fontWithName:@"ABeeZee-Regular" size:14]];
    [_titleLogin setFont:[UIFont fontWithName:@"Raleway-ExtraLight" size:28]];

    UIView *fieldEmail = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 10, 10)];
    _fieldEmail.leftViewMode = UITextFieldViewModeAlways;
    _fieldEmail.leftView     = fieldEmail;

    UIView *fieldPassword = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 10, 10)];
    _fieldPassword.leftViewMode = UITextFieldViewModeAlways;
    _fieldPassword.leftView     = fieldPassword;

    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (BOOL)validateEmail:(NSString *)emailStr {
    NSString *emailRegex = @"[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}";
    NSPredicate *emailTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", emailRegex];
    return [emailTest evaluateWithObject:emailStr];
}

- (IBAction)buttonRegister {
    _labelOutput.text = @"Register?";
}

- (IBAction)buttonLogin {
    if ([_fieldEmail.text length] > 0) {
        if(![self validateEmail:[_fieldEmail text]]){
            UIAlertView *message = [[UIAlertView alloc] initWithTitle:@"Email Error"
                                                              message:@"That's not a valid email!"
                                                             delegate:nil
                                                    cancelButtonTitle:@"OK"
                                                    otherButtonTitles:nil];
            [message show];
        }else{
            _labelOutput.text = @"Login?";
        }
    }else{
        UIAlertView *message = [[UIAlertView alloc] initWithTitle:@"Login Error"
                                                          message:@"Please enter your email"
                                                         delegate:nil
                                                cancelButtonTitle:@"OK"
                                                otherButtonTitles:nil];
        [message show];    
    }

}

- (IBAction)loginFacebook {
    if ([_fieldPassword.text length] > 15) {
        UIAlertView *message = [[UIAlertView alloc] initWithTitle:@"Password Error"
                                                          message:@"Password must be less than 15 characters."
                                                         delegate:nil
                                                cancelButtonTitle:@"OK"
                                                otherButtonTitles:nil];
        [message show];        
    }else{
        _labelOutput.text = @"Login with FB?";
    }
}

- (IBAction)loginTwitter {
   // _labelOutput.text = @"Login with Twitter ya?";
    UIAlertView *message = [[UIAlertView alloc] initWithTitle:@"Login Error"
                                                      message:@"Please enter your email correctly."
                                                     delegate:nil
                                            cancelButtonTitle:@"OK"
                                            otherButtonTitles:nil];
    [message show];
}
@end

如您所见，我用来显示警告框的代码重复了。有什么办法可以把这段类似的代码放在上面的某个地方，这样就可以通过将标题和消息作为变量来调用它:

    UIAlertView *message = [[UIAlertView alloc] initWithTitle:@"Login Error"
                                                      message:@"Please enter your email correctly."
                                                     delegate:nil
                                            cancelButtonTitle:@"OK"
                                            otherButtonTitles:nil];
    [message show];

在 PHP 世界里，这个方法叫做 function，但我不知道在 Objective-C 世界里叫什么名字。非常感谢。

Answer 1

要减少代码，为什么不创建另一种方法来显示 AlertBox？

- (void) alertWithTitle:(NSString *)title andMessage:(NSString *)msg
{
    UIAlertView *message = [[UIAlertView alloc] initWithTitle:title
                                                      message:msg
                                                     delegate:nil
                                            cancelButtonTitle:@"OK"
                                            otherButtonTitles:nil];
    [message show];
}

然后简单地调用:

[self alertWithTitle:(YOUR TITLE) andMessage:(YOUR MESSAGE)];