如何修复UITextView的文本长度？

Question

我有一个UITextView,用户可以在textView中写入最多160个字符.如何修复UITextView的最大文本长度？

Answer 1

这段代码也适用于复制/粘贴,但在尝试粘贴将使文本视图超出限制的字符数时也能应对这种情况.在这种情况下,只粘贴字符串的第一个字符.

#define MAX_LENGTH 15 // Whatever your limit is
- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text
{
    NSUInteger newLength = (textView.text.length - range.length) + text.length;
    if(newLength <= MAX_LENGTH)
    {
        return YES;
    } else {
        NSUInteger emptySpace = MAX_LENGTH - (textView.text.length - range.length);
        textView.text = [[[textView.text substringToIndex:range.location] 
                                            stringByAppendingString:[text substringToIndex:emptySpace]]
                                         stringByAppendingString:[textView.text substringFromIndex:(range.location + range.length)]];
        return NO;
    }
}

Answer 2

更换

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

同

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text

在这里回答

Answer 3

迟到了这个答案; manicaesar的解决方案对我不起作用.这是我对同一想法的实现:

#define MAX_LENGTH 140
- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)replacementText
{
    NSString *newText = [ textView.text stringByReplacingCharactersInRange: range withString: replacementText ];
    if( [newText length]<= MAX_LENGTH ){
        return YES;
    }
    // case where text length > MAX_LENGTH
    textView.text = [ newText substringToIndex: MAX_LENGTH ];
    return NO;
}