将限制设置为NSTextField [英] Set limit to NSTextField

问题描述

我需要为TextFields设置一个字符限制.我遵循了此 answer ，并且可以设置一个限制.但是现在当我按Enter键时，所有字符都消失了.出了什么问题?

I need to set a character limit for TextFields. I followed this answer and I was able to set a limit. But now when I press enter all characters are wiped out. What went wrong ?

- (BOOL)isPartialStringValid:(NSString *__autoreleasing *)partialStringPtr
       proposedSelectedRange:(NSRangePointer)proposedSelRangePtr
              originalString:(NSString *)origString
       originalSelectedRange:(NSRange)origSelRange
            errorDescription:(NSString *__autoreleasing *)error {
    if ([*partialStringPtr length] > maxLength)
        return NO;
    else
        return YES;
}

- (NSString *)stringForObjectValue:(id)obj {
    return (NSString*) obj;
}

- (BOOL)getObjectValue:(out __autoreleasing id *)obj
             forString:(NSString *)string
      errorDescription:(out NSString *__autoreleasing *)error {
    return YES;
}

- (NSAttributedString *)attributedStringForObjectValue:(id)obj
                                 withDefaultAttributes:(NSDictionary *)attrs {
    return (NSAttributedString*) obj;
}

推荐答案

如何将自己设置为NSTextField的委托并实现此委托方法?

How about setting yourself as delegate of the NSTextField an implement this delegate method?

- (void)textDidChange:(NSNotification *)aNotification

在这种情况下，您可以检查文本是否太长，然后将其剪切.

There you could check if the text is too long and then cut it if this is the case.

NSTextField *textField = (NSTextField *)[aNotification object];
if ([textField.stringValue length] > maxLength)
{
    textField.stringValue = [textField.stringValue substringWithRange:NSMakeRange(0,maxLength)];
}

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