最近公司涉及到作家助手的功能,能撤销输入的文字,并能反撤销被撤销掉的文字。
该功能类似ios系统的摇一摇撤销输入。
当时也特迷茫，不知道从何下手，后来搜索了大量的资料，终于完成了这个功能，现在就将该功能的实现写出来，共勉。
这个功能涉及到ios原生类：NSUndomanager。这个类挺强大。废话不多说,直接上代码。
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#import "ViewController.h"@interface ViewController ()<UITextViewDelegate>{ UITextView *_textView; NSUndoManager *_undomanager; NSInteger _length; UIButton *undobutton; UIButton *redobutton;}@end@implementation ViewController- (void)viewDidLoad { [super viewDidLoad]; UIBarButtonItem *undoItem = [[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemUndo target:self action:@selector(undoitem)]; UIBarButtonItem *redoItem = [[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemRedo target:self action:@selector(redoitem)]; self.navigationItem.leftBarButtonItem = undoItem; self.navigationItem.rightBarButtonItem = redoItem; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyBoardShow:) name:UIKeyboardWillShowNotification object:nil]; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyBoardHidden:) name:UIKeyboardWillHideNotification object:nil]; _length = 0;//初始化NSUndoManager _undomanager = [[NSUndoManager alloc] init]; _textView = [[UITextView alloc]initWithFrame:CGRectMake(0, 200, self.view.frame.size.width, 400)]; _textView.backgroundColor = [UIColor yellowColor]; _textView.delegate = self; _textView.font = [UIFont systemFontOfSize:15]; _textView.layer.cornerRadius = 5; _textView.layer.masksToBounds = YES; _textView.textColor = [UIColor blackColor]; _textView.text = @" ";//要设置初始文本,不然段落体现不出来。 NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init]; paragraphStyle.lineSpacing = 5; //行间距 paragraphStyle.firstLineHeadIndent = 30; /**首行缩进宽度*/ paragraphStyle.alignment = NSTextAlignmentLeft; NSDictionary *attributes = @{ NSFontAttributeName:[UIFont systemFontOfSize:13], NSParagraphStyleAttributeName:paragraphStyle }; _textView.attributedText = [[NSAttributedString alloc] initWithString:_textView.text attributes:attributes];//监听textview文本改动的通知 [[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(changeTextViewText) name:UITextViewTextDidChangeNotification object:nil]; [self.view addSubview:_textView];}-(void)redoitem{ //反撤销 [_undomanager redo];}-(void)undoitem{ //撤销 [_undomanager undo];}-(void)keyBoardShow:(NSNotification *)noti{ NSDictionary *dic = noti.userInfo; NSValue *aValue = [dic objectForKey:UIKeyboardFrameEndUserInfoKey]; CGRect keyboardRect = [aValue CGRectValue]; int height = keyboardRect.size.height; [_textView setContentInset:UIEdgeInsetsMake(0, 0, height, 0)];}-(void)keyBoardHidden:(NSNotification *)noti{ [_textView setContentInset:UIEdgeInsetsMake(0, 0, 0, 0)];}- (void)setMyObjectTitle:(NSString *)newTitle{ //判断当前NSUndoManager的状态，是处于撤销或者反撤销的状态-(void)textViewDidChange:(UITextView *)textView if (_undomanager.isUndoing) { NSInteger length = newTitle.length; if (_textView.text.length>0) { //获取 _textView.text = [_textView.text substringWithRange:NSMakeRange(0, _textView.text.length - length)]; [_undomanager registerUndoWithTarget:self selector:@selector(setMyObjectTitle:) object:newTitle]; } }else if (_undomanager.isRedoing){ _textView.text = [_textView.text stringByAppendingString:newTitle]; [_undomanager registerUndoWithTarget:self selector:@selector(setMyObjectTitle:) object:newTitle]; }else{ NSString *currentText = _textView.text; if (newTitle != currentText) { _textView.text = currentText; [_undomanager registerUndoWithTarget:self selector:@selector(setMyObjectTitle:) object:newTitle]; }else{ _textView.text = newTitle; } }}-(void)changeTextViewText{ if (_textView.text.length>0) { undobutton.enabled = YES; }else{ undobutton.enabled = NO; redobutton.enabled = NO; } NSString *text ; if (_length != 0) { NSInteger textLength = _textView.text.length; if (textLength > _length) { NSInteger newLength = textLength - _length; text = [NSString stringWithFormat:@"%@",[_textView.text substringWithRange:NSMakeRange(_length, newLength)]]; }else{ text = _textView.text; } }else{ text = _textView.text; } _length = _textView.text.length; [self setMyObjectTitle:text];} |
总结
以上所述是小编给大家介绍的iOS UITextView 首行缩进 撤销输入 反撤销输入的实现代码，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对服务器之家网站的支持！
原文链接：http://blog.csdn.net/m0_37815556/article/details/78047669
