xcode 如何在xcode中单击按钮时调用返回bool值的函数？

how to call a function returning bool value on button's click in xcode?

提问by Ram Singh

I am new to the ios development, I am just trying to create a simple application for calculations, So for that i have used to textboxes and i want to allow only the numeric values for these. i have already set the keyboardproperty to numeric pad. Now i want to do it programmatically for that i found the following function from checks for the String contains Numeric value only

我是 ios 开发的新手，我只是想创建一个简单的计算应用程序，因此我已经习惯了文本框，我只想允许这些数字值。我已经将键盘属性设置为数字键盘。现在我想以编程方式执行此操作，因为我从检查字符串中发现以下函数仅包含数字值

+(BOOL) checkforNumeric:(NSString*) str 
{ 
NSString *strMatchstring=@"\b([0-9%_.+\-]+)\b"; 
NSPredicate *textpredicate=[NSPredicate predicateWithFormat:@"SELF MATCHES %@", strMatchstring]; 
if(![textpredicate evaluateWithObject:str]) 
{ 
//////NSLog(@"Invalid email address found"); 
UIAlertView *objAlert = [[UIAlertView alloc] initWithTitle:APP_NAME message:@"please enter valid text." delegate:nil cancelButtonTitle:nil otherButtonTitles:@"Close",nil]; 
[objAlert show]; 
[objAlert release]; 
return FALSE; 
} 
return TRUE; 
} 

Now i want to call it on button's click, i have tried some ways but it always shows error. Please help me how can i utilize this function in button's click.

现在我想在单击按钮时调用它，我尝试了一些方法，但它总是显示错误。请帮助我如何在按钮的点击中使用此功能。

My Actual code of button is:

我的按钮实际代码是：

-(IBAction)button{
if (firstValue.text.length>0 && secondvalue.text.length>0) {

    label.text=  [ [NSString alloc] initWithFormat:@"Result is:  %.2f", ([firstValue.text floatValue]) * ([secondvalue.text floatValue])];

}
else if (firstValue.text.length==0 && secondvalue.text.length==0){
    //label.text=    @"please enter the values.";
    UIAlertView  *alert = [[UIAlertView alloc] initWithTitle:@"Alert" message:@"Please Enetr First Value and second value." delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles:nil];
    [alert show];
    [alert release];
}else if (firstValue.text.length==0) {
    //label.text=    @"please enter the first values.";
    UIAlertView *alert=[[UIAlertView alloc] initWithTitle:@"Alert" message:@"Please Enter First Value" delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles:nil];
    [alert show];
    [alert release];
}else if (secondvalue.text.length==0) {
    //label.text=    @"please enter the second values.";
    UIAlertView *alert=[[UIAlertView alloc] initWithTitle:@"Alert" message:@"Please Eneter Second Value" delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles:nil];
    [alert show];
    [alert release];
}
}

Please help me.

请帮我。

I have tried the following ways for this:

为此，我尝试了以下方法：

BOOL *test= checkforNumeric(firstValue.text);

回答by Shubhank

call your Method like this

像这样调用你的方法

BOOL isValidString_withNoNumbers = [self checkforNumeric: firstValue.text];
if(isValidString_withNoNumbers)
{
     //your code
}

and also you should change the method to instance method

并且您应该将方法更改为实例方法

so it should be

所以应该是

-(BOOL) checkforNumeric:(NSString*) str // - for instance method //+ for class methods

回答by P.J

Make your following line this way :-

以这种方式制作以下行：-

-(BOOL) checkforNumeric:(NSString*) str 

and declare it in your .h file

并在您的 .h 文件中声明它

回答by Simone Pistecchia

if your method is in the same class, you must redifine your method, with -

如果你的方法在同一个类中，你必须重新定义你的方法，用 -

-(BOOL) checkforNumeric:(NSString*) str 

and call it with:

并调用它：

[self checkforNumeric: firstValue.text];

if you define +(BOOL) checkforNumeric:(NSString*) strin another class like MyCheckClass, you must import MycheckClass and call it:

如果您+(BOOL) checkforNumeric:(NSString*) str在另一个类（如 MyCheckClass ）中定义，则必须导入 MycheckClass 并调用它：

BOOL isOk = [MyCheckClass checkforNumeric:firstValue.text];