iOS UITextView 首行缩进 撤销输入 反撤销输入的实现代码
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。
#import"ViewController.h" @interfaceViewController(){ UITextView*_textView; NSUndoManager*_undomanager; NSInteger_length; UIButton*undobutton; UIButton*redobutton; } @end @implementationViewController -(void)viewDidLoad{ [superviewDidLoad]; UIBarButtonItem*undoItem=[[UIBarButtonItemalloc]initWithBarButtonSystemItem:UIBarButtonSystemItemUndotarget:selfaction:@selector(undoitem)]; UIBarButtonItem*redoItem=[[UIBarButtonItemalloc]initWithBarButtonSystemItem:UIBarButtonSystemItemRedotarget:selfaction:@selector(redoitem)]; self.navigationItem.leftBarButtonItem=undoItem; self.navigationItem.rightBarButtonItem=redoItem; [[NSNotificationCenterdefaultCenter]addObserver:selfselector:@selector(keyBoardShow:)name:UIKeyboardWillShowNotificationobject:nil]; [[NSNotificationCenterdefaultCenter]addObserver:selfselector:@selector(keyBoardHidden:)name:UIKeyboardWillHideNotificationobject:nil]; _length=0; //初始化NSUndoManager _undomanager=[[NSUndoManageralloc]init]; _textView=[[UITextViewalloc]initWithFrame:CGRectMake(0,200,self.view.frame.size.width,400)]; _textView.backgroundColor=[UIColoryellowColor]; _textView.delegate=self; _textView.font=[UIFontsystemFontOfSize:15]; _textView.layer.cornerRadius=5; _textView.layer.masksToBounds=YES; _textView.textColor=[UIColorblackColor]; _textView.text=@"";//要设置初始文本,不然段落体现不出来。 NSMutableParagraphStyle*paragraphStyle=[[NSMutableParagraphStylealloc]init]; paragraphStyle.lineSpacing=5;//行间距 paragraphStyle.firstLineHeadIndent=30;/**首行缩进宽度*/ paragraphStyle.alignment=NSTextAlignmentLeft; NSDictionary*attributes=@{ NSFontAttributeName:[UIFontsystemFontOfSize:13], NSParagraphStyleAttributeName:paragraphStyle }; _textView.attributedText=[[NSAttributedStringalloc]initWithString:_textView.textattributes:attributes]; //监听textview文本改动的通知 [[NSNotificationCenterdefaultCenter]addObserver:selfselector:@selector(changeTextViewText)name:UITextViewTextDidChangeNotificationobject:nil]; [self.viewaddSubview:_textView]; } -(void)redoitem{ //反撤销 [_undomanagerredo]; } -(void)undoitem{ //撤销 [_undomanagerundo]; } -(void)keyBoardShow:(NSNotification*)noti{ NSDictionary*dic=noti.userInfo; NSValue*aValue=[dicobjectForKey:UIKeyboardFrameEndUserInfoKey]; CGRectkeyboardRect=[aValueCGRectValue]; intheight=keyboardRect.size.height; [_textViewsetContentInset:UIEdgeInsetsMake(0,0,height,0)]; } -(void)keyBoardHidden:(NSNotification*)noti{ [_textViewsetContentInset: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){ NSIntegerlength=newTitle.length; if(_textView.text.length>0){ //获取 _textView.text=[_textView.textsubstringWithRange:NSMakeRange(0,_textView.text.length-length)]; [_undomanagerregisterUndoWithTarget:self selector:@selector(setMyObjectTitle:) object:newTitle]; } }elseif(_undomanager.isRedoing){ _textView.text=[_textView.textstringByAppendingString:newTitle]; [_undomanagerregisterUndoWithTarget:self selector:@selector(setMyObjectTitle:) object:newTitle]; }else{ NSString*currentText=_textView.text; if(newTitle!=currentText){ _textView.text=currentText; [_undomanagerregisterUndoWithTarget: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){ NSIntegertextLength=_textView.text.length; if(textLength>_length){ NSIntegernewLength=textLength-_length; text=[NSStringstringWithFormat:@"%@",[_textView.textsubstringWithRange:NSMakeRange(_length,newLength)]]; }else{ text=_textView.text; } }else{ text=_textView.text; } _length=_textView.text.length; [selfsetMyObjectTitle:text]; }
总结
以上所述是小编给大家介绍的iOSUITextView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毛票票网站的支持！