IOS中的UITextView和UITextField都是文本输入控件并都能够调用系统键盘。本次特酷把介绍UITextView和UITextField的区别。

简单来说，UITextView和UITextField最大的区别是：UITextView支持多行输入，而UITextField只能单行输入。实际上，UITextView继承自UIScrollView,UITextField继承自UIView[UIControl]。在使用上我们完全可以把UITextView看作是UITextField的加强版。下面是他们各自的代理协议，可以看出，他们的代理协议很相似，事实上用法也相通。

折叠展开C/C++ Code复制内容到剪贴板UITextView的协议UITextViewDelegate: 

@protocol UITextViewDelegate <NSObject, UIScrollViewDelegate> 

@optional 

- (BOOL)textViewShouldBeginEditing:(UITextView *)textView; 

- (BOOL)textViewShouldEndEditing:(UITextView *)textView; 

- (void)textViewDidBeginEditing:(UITextView *)textView; 

- (void)textViewDidEndEditing:(UITextView *)textView; 

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

- (void)textViewDidChange:(UITextView *)textView; 

- (void)textViewDidChangeSelection:(UITextView *)textView; 

@end 

UITextField的协议UITextFieldDelegate: 

@protocol UITextFieldDelegate <NSObject> 

@optional 

- (BOOL)textFieldShouldBeginEditing:(UITextField *)textField;        // return NO to disallow editing. 

- (void)textFieldDidBeginEditing:(UITextField *)textField;           // became first responder 

- (BOOL)textFieldShouldEndEditing:(UITextField *)textField;          // return YES to allow editing to stop and to resign first responder status. NO to disallow the editing session to end 

- (void)textFieldDidEndEditing:(UITextField *)textField;             // may be called if forced even if shouldEndEditing returns NO (e.g. view removed from window) or endEditing:YES called 

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string;   // return NO to not change text 

- (BOOL)textFieldShouldClear:(UITextField *)textField;               // called when clear button pressed. return NO to ignore (no notifications) 

- (BOOL)textFieldShouldReturn:(UITextField *)textField;              // called when 'return' key pressed. return NO to ignore. 

@end 

在这里值得一提的是IOS中常常需要有限制用户输入字数的要求，我们可以如下处理：

1，UITextView

我们可以在- (void)textViewDidChange:(UITextView *)textView[检测到输入变化的时候执行]和

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text[超过一定字数返回NO即可]

2，UITextField

简单的方法只能在 - (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string; 方法中处理。

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