// UITextField的初始化

UITextField textField = [[UITextField alloc] initWithFrame:CGRectMake(0, 0, 320,30)];

//外框类型

[textField setBorderStyle:UITextBorderStyleRoundedRect];

//默认显示的字

textField.placeholder = @"默认显示的字";

//密码

textField.secureTextEntry = YES;

//是否纠错

text.autocorrectionType = UITextAutocorrectionTypeNo;

typedef enum {

UITextAutocorrectionTypeDefault, 默认

UITextAutocorrectionTypeNo,   不自动纠错

UITextAutocorrectionTypeYes,  自动纠错

} UITextAutocorrectionType;

//首字母是否大写

textField.autocapitalizationType = UITextAutocapitalizationTypeNone;

typedef enum {

UITextAutocapitalizationTypeNone, 不自动大写

UITextAutocapitalizationTypeWords,  单词首字母大写

UITextAutocapitalizationTypeSentences,  句子的首字母大写

UITextAutocapitalizationTypeAllCharacters, 所有字母都大写

} UITextAutocapitalizationType;

textField.returnKeyType = UIReturnKeyDone;
 textField.clearButtonMode = UITextFieldViewModeWhileEditing; //编辑时会出现个修改X

//按return键返回
-(IBAction) textFieldDone:(id) sender
{
[textFieldName resignFirstResponder];
}
最右侧加图片是以下代码,
   UIImageView *imgv=[[UIImageView alloc] initWithImage:[UIImage imageNamed:@"right.png"]];
   text.rightView=imgv;
   text.rightViewMode = UITextFieldViewModeAlways;

如果是在最左侧加图片就换成:
text.leftView=imgv;
text.leftViewMode = UITextFieldViewModeAlways;    
UITextField 继承自 UIControl,此类中有一个属性contentVerticalAlignment
所以想让UITextField里面的text垂直居中可以这样写:
text.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter;

//删除文本框中选中的文本
[textView delete: nil];

//限制长度

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
   if (range.location >= MAX_LENGTH)
       return NO; // return NO to not change text
   return YES;
}
if (textField.text.length >= 10 && range.length == 0)
   return NO;
return YES;
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
if ([textField.text length] > MAXLENGTH)
{
 textField.text = [textField.text substringToIndex:MAXLENGTH-1];
 return NO;
}
return YES;

}

// UITextFieldDelegate 协议

<UITextFieldDelegate>

//按键盘完成时取消焦点：

- (BOOL)textFieldShouldReturn:(UITextField *)textField {

[textField resignFirstResponder]; //取消焦点／隐藏键盘

return YES;

}

//设置焦点：
[UITextField becomeFirstResponder];

//绑定事件
textField.delegate = self;

ps:

有时可能会遇到 textFieldShouldReturn 函数写了，但是按键到 return 无法让键盘消失。这是因为你的文本框没有添加委托。添加委托的方法，右键文本框，把 outlets 下的＋拉到 file's owner 上就可以了。 或者在加载事件中添加t xtLength.delegate=self;