在UITextView上设置最大行数

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- (BOOL) textView:(UITextView *)textView
    shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text
    static const NSUInteger MAX_NUMBER_OF_LINES_ALLOWED = 3;
    NSMutableString *t = [NSMutableString stringWithString:
        self.textView.text];
    [t replaceCharactersInRange: range withString: text];
    NSUInteger numberOfLines = 0;
    for (NSUInteger i = 0; i < t.length; i++) {
        if ([[NSCharacterSet newlineCharacterSet]
                characterIsMember: [t characterAtIndex: i]]) {
            numberOfLines++;
    return (numberOfLines < MAX_NUMBER_OF_LINES_ALLOWED);
}

- (id)initWithFrame:(CGRect)frame
    self = [super initWithFrame:frame];
    if (self) {
        self.AutoresizingMask   = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
        self.AutocorrectionType = UITextAutocorrectionTypeNo;
        self.KeyboardAppearance = UIKeyboardAppearanceAlert;
        self.font               = [UIFont fontWithName:@"Avenir" size:14];
        self.maximumNumberOfLinesAllowed = 4;
        self.delegate           = self;
    return self;
- (BOOL)textView:(UITextView *)aTextView shouldChangeTextInRange:(NSRange)aRange replacementText:(NSString*)aText
    NSMutableString *t = [NSMutableString stringWithString: self.text];
    [t replaceCharactersInRange: aRange withString: aText];
    // First check for standard '\n' (newline) type characters.
    NSUInteger numberOfLines = 0;
    for (NSUInteger i = 0; i < t.length; i++) {
        if ([[NSCharacterSet newlineCharacterSet] characterIsMember: [t characterAtIndex: i]]) {
            numberOfLines++;
    if (numberOfLines >= self.maximumNumberOfLinesAllowed)
        return NO;
    // Now check for word wrapping onto newline.
    NSAttributedString *t2 = [[NSAttributedString alloc]
                             initWithString:[NSMutableString stringWithString:t] attributes:@{NSFontAttributeName:self.font}];
    __block NSInteger lineCount = 0;
    CGFloat maxWidth   = self.frame.size.width;
    NSLog(@"maxWidth = %.02f", maxWidth);
    NSTextContainer *tc = [[NSTextContainer alloc] initWithSize:CGSizeMake(maxWidth, CGFLOAT_MAX)];
    NSLayoutManager *lm = [[NSLayoutManager alloc] init];
    NSTextStorage   *ts = [[NSTextStorage alloc] initWithAttributedString:t2];
    [ts addLayoutManager:lm];
    [lm addTextContainer:tc];
    [lm enumerateLineFragmentsForGlyphRange:NSMakeRange(0,lm.numberOfGlyphs)
                                 usingBlock:^(CGRect rect,
                                              CGRect usedRect,
                                              NSTextContainer *textContainer,
                                              NSRange glyphRange,
                                              BOOL *stop)
         lineCount++;
//    NSLog(@"%d", lineCount);
    return (lineCount <= self.maximumNumberOfLinesAllowed);
}

- (void)textViewDidChange:(UITextView *)textView
    NSUInteger maxNumberOfLines = 5;
    NSUInteger numLines = textView.contentSize.height/textView.font.lineHeight;
    if (numLines > maxNumberOfLines)

在UITextView上设置最大行数

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