效果圖：
1.自定義一個TextField繼承自UITextField：
.h檔案

#import <UIKit/UIKit.h>

@interface AMPTextField : UITextField

@end

2.在.m檔案中重寫- (void)drawRect:(CGRect)rect {}方法

#import "AMPTextField.h"

@implementation AMPTextField


- (void)drawRect:(CGRect)rect {
    [super drawRect:rect];
    UIToolbar *bar = [[UIToolbar alloc] initWithFrame:CGRectMake(0
 
,0, AMPScreenWidth,44)];
    UIButton *button = [[UIButton alloc] initWithFrame:CGRectMake(AMPScreenWidth - 60, 7,50, 30)];
    [button setTitle:@"完成"forState:UIControlStateNormal];
    [button setTitleColor:[UIColor blueColor] forState:UIControlStateNormal];
    button.layer.borderColor = [UIColor blueColor].CGColor
 
;
    button.layer.borderWidth =1;
    button.layer.cornerRadius =3;
    [bar addSubview:button];
    self.inputAccessoryView = bar;

    [button addTarget:self action:@selector(print)forControlEvents:UIControlEventTouchUpInside];
}

- (void) print {
    [self resignFirstResponder];
}

@end

3.AMPTextField的鍵盤就會有完成按鈕，點選完成收回鍵盤。