UIPasteboard的使用

1.概述

UIPasteboard是ios中访问粘贴板的原生控件，可分为系统等级的和app等级的，系统等级的独立于app，可以复制一个app的内容到另一个app；app等级的只能在app内进行复制和粘贴；它们分别由+ (nullable UIPasteboard *)pasteboardWithName:(NSString *)pasteboardName create:(BOOL)create这两个类方法进行创建。

2.数据类型

可以复制在粘贴板的数据类型有NSString、UIImage、NSURL、UIColor、NSData以及由这些类型元素组成的数组。可分别由它们的set方法将数据放在粘贴板中，如NSString：

UIPasteboard* pasteboard = [UIPasteboard generalPasteboard];
[pasteboard setString:@"复制的字符串内容"];

3.使用方法

在ios中，支持UIPasteboard原生控件只有UITextField 、UITextView、UIWebView这三个,如果想自定义一个控件能够使用UIPasteboard，需要在定义的时候重载 -(BOOL)canBecomeFirstResponder和 -(BOOL)canPerformAction:(SEL)action withSender:(id)sender这两个方法，前者设置控件可称为第一响应器，后者决定这个控件能够使用复制、剪切、选中、全选、粘贴等的哪一种或几种功能,并重载对应的-(void)copy:(id)sender、-(void)cut:(id)sender、-(void)select:(id)sender、-(void)selectAll:(id)sender、-(void)paste:(id)sender方法，在这几个方法中处理事件,UIMenuController负责显示UI。

4.复制图片的简单例子

创建一个CopyView

#import "CopyView.h"
@interface CopyView ()
@property (strong, nonatomic) UIImageView* img1;
@property (strong, nonatomic) UIImageView* img2;
@end

@implementation CopyView
-(UIImageView *)img1{
    if (_img1 == nil) {
        _img1 = [[UIImageView alloc] initWithFrame:CGRectMake(10.0f, 20.0f, 100.0f, 100.0f)];
        NSString* path = [[NSBundle mainBundle] pathForResource:@"NetworldImage" ofType:@"jpg"];
        _img1.image = [UIImage imageWithContentsOfFile:path];
    }
    return _img1;
}

-(UIImageView *)img2{
    if (_img2 == nil) {
          _img2 = [[UIImageView alloc] initWithFrame:CGRectMake(CGRectGetMaxX(self.img1.frame)+50.0f, 20.0f, 100.0f, 100.0f)];
        _img2.backgroundColor = [UIColor lightGrayColor];
    }
    return _img2;
}

- (instancetype)initWithFrame:(CGRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
        self.backgroundColor = [UIColor whiteColor];
        [self addSubview:self.img1];
        [self addSubview:self.img2];
    }
    return self;
}

-(BOOL)canBecomeFirstResponder{
    return YES;
}
-(BOOL)canPerformAction:(SEL)action withSender:(id)sender{
    NSArray* methodNameArr = @[@"copy:",@"cut:",@"select:",@"selectAll:",@"paste:"];
    if ([methodNameArr containsObject:NSStringFromSelector(action)]) {
        return YES;
    }
    return [super canPerformAction:action withSender:sender];
}

-(void)copy:(id)sender{
    UIPasteboard* pasteboard = [UIPasteboard generalPasteboard];
    [pasteboard setImage:self.img1.image];
}

-(void)paste:(id)sender{
    UIPasteboard* pasteboard = [UIPasteboard generalPasteboard];
    self.img2.image = [pasteboard image];
}

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
    [self becomeFirstResponder];
    UIMenuController* menuController = [UIMenuController sharedMenuController];
    [menuController setTargetRect:self.img1.frame inView:self];
    [menuController setMenuVisible:YES animated:YES];
}

@end

在controller中

#import "ViewController.h"
#import "CopyView.h"

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    CopyView* cv = [[CopyView alloc] initWithFrame:self.view.bounds];
    self.view = cv;
}

@end