UI控件（UITextField）

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    UITextField* textField1 = [[UITextField alloc] init];
    
    //设置代理表示实现协议 UITextFieldDelegate
    textField1.delegate = self;
    textField1.frame = CGRectMake( 20, 120, 280, 30 );
    //    边框样式
    //    typedef enum {
    //        UITextBorderStyleNone,            无边框
    //        UITextBorderStyleLine,            直线边框
    //        UITextBorderStyleBezel,           左边框、上边框加粗
    //        UITextBorderStyleRoundedRect      圆角
    //    } UITextBorderStyle;
    textField1.borderStyle = UITextBorderStyleRoundedRect;
    textField1.text = @"hello,textfield";
    textField1.placeholder = @"please input the text";
    
    //设置字体及大小
    textField1.font = [UIFont fontWithName:@"Arial" size:10.0f];
    //设置字体颜色
    textField1.textColor = [UIColor blueColor];
    //    typedef enum {
    //        UITextFieldViewModeNever,             重不出现
    //        UITextFieldViewModeWhileEditing,      编辑时出现
    //        UITextFieldViewModeUnlessEditing,     除了编辑外都出现
    //        UITextFieldViewModeAlways             一直出现
    //    } UITextFieldViewMode;
    textField1.clearButtonMode = UITextFieldViewModeAlways;
    
    //采用星号加密显示
    textField1.secureTextEntry = NO;
    
    //定义弹出的软键盘类型
    //UIKeyboardTypeDefault     默认全部
    //UIKeyboardTypeNumberPad   数字键盘
    //类型较多，此处省略
    textField1.keyboardType = UIKeyboardTypeDefault;
    
    //定义软键盘上的回车按键的样式
    //    UIReturnKeyDefault,   默认 灰色按钮，标有Return
    //    UIReturnKeyGo,        标有Go的蓝色按钮
    //    类型较多此处省略
    textField1.returnKeyType = UIReturnKeyDefault;
    
    //左侧或右侧增加图片
    UIImageView *image=[[UIImageView alloc] initWithImage:[UIImage imageNamed:@"person.png"]];
    textField1.leftView=image;
    textField1.leftViewMode = UITextFieldViewModeAlways;
    
    
    [self.view addSubview:textField1];
}

#pragma mark - TextField Delegates

//开始编辑时出发回调
-(void)textFieldDidBeginEditing:(UITextField *)textField{
    NSLog(@"%s", __FUNCTION__);
}

//结束编辑时出发回调(软键盘消失)
-(void)textFieldDidEndEditing:(UITextField *)textField{
    NSLog(@"%s", __FUNCTION__);
}

//回车时被回调
-(BOOL) textFieldShouldReturn:(UITextField *)textField{
    NSLog(@"%s", __FUNCTION__);
    [textField resignFirstResponder];//若该行注释则软件盘在回车后部消失
    return YES;
}

@end