Objective C iPhone 子类化 UITextField catch 值已更改

Question

我对 UITextField 进行了子类化，因此我可以为其创建一些自定义行为。以下是我的类：

DataboundTextField.h

#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
#import "TestEntities.h"

@interface DataboundTextField : UITextField <UITextFieldDelegate> {
NSString *valueMember;
NSString *displayValueMember;
ODataObject *boundEntity;

}
@property (nonatomic, retain) NSString *valueMember;
@property (nonatomic, retain) NSString *displayValueMember;
@property (nonatomic, retain) ODataObject *boundEntity;
-(void)SetupDataBinding:(ODataObject*)oDataEntity ValueMember:(NSString*)valMemberID    DisplayValueMember:(NSString*)disValMember;

@end

DataboundTextField.m

#import "DataboundTextField.h"

@implementation DataboundTextField

@synthesize valueMember;
@synthesize displayValueMember;
@synthesize boundEntity;

-(id) initWithCoder:(NSCoder *)aDecoder{
if ((self = [super initWithCoder:aDecoder]))
{
    self.delegate = self;
}

return self;
}



-(void)SetupDataBinding:(ODataObject*)oDataEntity ValueMember:(NSString*)valMemberID DisplayValueMember:(NSString*)disValMember{

}

-(BOOL) textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
return YES;
}

@end

如何覆盖 ValueChanged 事件？无论我怎么努力，我似乎​​都无法抓住它。我想做的就是在视图上添加这些子类文本字段之一并捕获该事件并处理它。

请帮忙。

提前致谢

Answer 1

根据 UITextFieldDelegate 的文档，您可以使用

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string

每当用户在文本字段中键入新字符或删除现有字符时，文本字段都会调用此方法。

确保设置 UITextField 的 delegate 属性：

- (id)init
{
    if ((self = [super init]))
    {
        self.delegate = self;
    }
}

Answer 2

这是我用来只允许某些字符的方法，以及文本字段允许使用多少个字符：

- (BOOL)textField:(UITextField *)theTextField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
    /*  allow only these characters in the textField  */   
    NSCharacterSet *myCharSet = [NSCharacterSet characterSetWithCharactersInString:@" abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890|:.@~_-+#!{}%*"];
    for (int i = 0; i < [string length]; i++) {
        unichar c = [string characterAtIndex:i];
        if (![myCharSet characterIsMember:c]) {
            return NO;
        }
    }
    /*  choose how many characters the textField can have  */
    NSUInteger newLength = [theTextField.text length] + [string length] - range.length;
    return (newLength > 28) ? NO : YES;
}