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

正如你在那里看到的那样，我用来显示警告框的代码会重复出现。有没有办法把这个类似的代码放在那里，所以只需将Title和Message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世界中，这个方法命名为function，但我不知道Objective-C世界中的名字是什么。非常感谢你。

Answer 1

要减少代码，为什么不创建另一种方法来显示警告框？

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

然后简单地致电：

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

Answer 2

你写了一些方法，你考虑过再写一个吗？ E.g。

- (void) showAlertWithTitle:(NSString *)title andMessage:(NSString *)message
{
    ...
}

然后当您需要警报时调用此方法，例如：

[self showAlertWithTitle:@"Login Error" andMessage:@"Please enter your email correctly."];

HTH

iOS：简化的UIAlertView代码，因此可以一次又一次地使用它

2 个答案: