objective-c自定义uitextview（placeholder，长按换行，文字位置文字间距等）(代码片段)

#import "TextView.h"

@interface TextView ()


    NSInteger b_index;

@end

@implementation TextView

CGFloat const UI_PLACEHOLDER_TEXT_CHANGED_ANIMATION_DURATION = 0.25;

- (void)dealloc

    [[NSNotificationCenter defaultCenter] removeObserver:self];
#if __has_feature(objc_arc)
#else
    [_placeHolderLabel release]; _placeHolderLabel = nil;
    [_placeholderColor release]; _placeholderColor = nil;
    [_placeholder release]; _placeholder = nil;
    [super dealloc];
#endif


- (void)awakeFromNib

    [super awakeFromNib];
    if (!self.placeholder) 
        _placeholder = @"";
    
    
    if (!self.placeholderColor) 
        [self setPlaceholderColor:[UIColor lightGrayColor]];
    
    
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textChanged:) name:UITextViewTextDidChangeNotification object:nil];


- (id)initWithFrame:(CGRect)frame

    if( (self = [super initWithFrame:frame]) )
    
        _placeholder = @"";
        self.tintColor = [UIColor colorWithHexString:@"#B1B5BA"];
        self.returnKeyType = UIReturnKeyDone;
        [self setPlaceholderColor:[UIColor lightGrayColor]];
        
         //设置菜单

        UIMenuItem *menuItem = [[UIMenuItem alloc]initWithTitle:@"换行" action:@selector(selfMenu:)];
        UIMenuController *menuController = [UIMenuController sharedMenuController];
        [menuController setMenuItems:[NSArray arrayWithObject:menuItem]];
        [menuController setMenuVisible:NO];

        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textChanged:) name:UITextViewTextDidChangeNotification object:nil];
    
    return self;


-(BOOL)canPerformAction:(SEL)action withSender:(id)sender
    if (action == @selector(selfMenu:)) 
        return YES;

    else if(action ==@selector(copy:) || action ==@selector(selectAll:) || action ==@selector(cut:) || action ==@selector(select:))
        BOOL isAppear = [super canPerformAction:action withSender:sender];
        return isAppear;
    
    return NO;



-(void)selfMenu:(id)sender
    self.text = [self.text stringByAppendingString:@"
"];


- (void)textChanged:(NSNotification *)notification

    if([[self placeholder] length] == 0)
    
        return;
    
    
    [UIView animateWithDuration:UI_PLACEHOLDER_TEXT_CHANGED_ANIMATION_DURATION animations:^
        if([[self text] length] == 0)
        
            [[self viewWithTag:999] setAlpha:1];
        
        else
        
            [[self viewWithTag:999] setAlpha:0];
        
    ];
    


- (void)setText:(NSString *)text 
    [super setText:text];
    [self textChanged:nil];


- (void)drawRect:(CGRect)rect

    if( [[self placeholder] length] > 0 )
    
        UIEdgeInsets insets = self.textContainerInset;
        if (_placeHolderLabel == nil )
        
            
            _placeHolderLabel = [[UILabel alloc] initWithFrame:CGRectMake(insets.left+10,5,self.bounds.size.width - (insets.left +insets.right+20),1.0)];//insets.top
            _placeHolderLabel.lineBreakMode = NSLineBreakByWordWrapping;
            _placeHolderLabel.font = self.font;
            _placeHolderLabel.backgroundColor = [UIColor clearColor];
            _placeHolderLabel.textColor = self.placeholderColor;
            _placeHolderLabel.alpha = 0;
            _placeHolderLabel.tag = 999;
            [self addSubview:_placeHolderLabel];
        
        _placeHolderLabel.text = self.placeholder;
        [_placeHolderLabel sizeToFit];//insets.top
        [_placeHolderLabel setFrame:CGRectMake(insets.left+10,5,self.bounds.size.width - (insets.left +insets.right),CGRectGetHeight(_placeHolderLabel.frame))];
        [self sendSubviewToBack:_placeHolderLabel];
    
    
    if( [[self text] length] == 0 && [[self placeholder] length] > 0 )
    
        [[self viewWithTag:999] setAlpha:1];
    
    [super drawRect:rect];

- (void)setPlaceholder:(NSString *)placeholder
    if (_placeholder != placeholder) 
        _placeholder = placeholder;
        [self setNeedsDisplay];
    
    



-(void)textViewlineSpacing:(TextView *)textView
    
    if (textView.text.length < 1) 
        textView.text = @"间距";
    
    NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
    paragraphStyle.lineSpacing = 4;// 字体的行间距
    NSDictionary *attributes = @
                                 
                                 NSFontAttributeName:[UIFont systemFontOfSize:13],
                                 
                                 NSParagraphStyleAttributeName:paragraphStyle
                                 
                                 ;
    
    textView.attributedText = [[NSAttributedString alloc] initWithString:self.text attributes:attributes];
    textView.textColor = kTextColor_Black;
    if ([textView.text isEqualToString:@"间距"]) 
        textView.attributedText = [[NSAttributedString alloc] initWithString:@"" attributes:attributes];
    


@end

#import <UIKit/UIKit.h>

@interface TextView : UITextView

@property (nonatomic, strong) NSString *placeholder;
@property (nonatomic, strong) UIColor *placeholderColor;

@property (nonatomic, strong) UILabel *placeHolderLabel;


-(void)textChanged:(NSNotification*)notification;

-(void)textViewlineSpacing:(TextView *)textView;

@end