DatePicker显示时间的控件：有默认宽度，不用设置数据源和代理；

如何改成中文的？

1> 查看当前系统是否为中文，把模拟器改成中文；

2> 属性，locale选择地区；

如果默认显示不符合需求，时间有四种模式可以设置，在model中进行设置，时间可以自定义。

设置最小时间和最大时间，超过就会自动回到最小时间；

最大的用途在于自定义键盘：弹出一个日期选择器出来；

UIDatePicker *picker = [[UIDatePicker alloc] init];

[picker setLocale:[NSLocale localeWithLocaleIdentifier:@"zh-CN"]];

picker.datePickerMode = UIDatePickerModeDate;

_viewfield = [[UITextField alloc] initWithFrame:CGRectMake(20, button.frame.origin.y + 30 +10, [UIScreen mainScreen].bounds.size.width-40, 40)];

_viewfield.keyboardType = UIKeyboardTypeDefault;

_viewfield.placeholder = @"请输入密码";

_viewfield.leftViewMode = UITextFieldViewModeAlways;

_viewfield.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter;

_viewfield.textColor = [UIColor darkTextColor];

_viewfield.font = [UIFont fontWithName:@"Arial" size:20.0];

_viewfield.clearButtonMode = UITextFieldViewModeAlways;

_viewfield.borderStyle = UITextBorderStyleRoundedRect;

_viewfield.secureTextEntry = YES;

_viewfield.returnKeyType = UIReturnKeyDone;

_viewfield.delegate = self;

[self.view addSubview:_viewfield];

_viewfield.inputView = picker;

UIToolbar *tool = [[UIToolbar alloc] init];

tool.barTintColor = [UIColor brownColor];

tool.frame = CGRectMake(0, 0, [UIScreen mainScreen].bounds.size.width, 44);

UIBarButtonItem *item1 = [[UIBarButtonItem alloc] initWithTitle:@"上一个" style:UIBarButtonItemStylePlain target:self action:@selector(itemClick:)];

UIBarButtonItem *item2 = [[UIBarButtonItem alloc] initWithTitle:@"下一个" style:UIBarButtonItemStylePlain target:self action:@selector(itemClick:)];

UIBarButtonItem *space = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:nil action:nil];

UIBarButtonItem *item3 = [[UIBarButtonItem alloc] initWithTitle:@"完成" style:UIBarButtonItemStylePlain target:self action:@selector(itemClick:)];

tool.items = @[item1, item2, space, item3];

_viewfield.inputAccessoryView = tool;