UIView的无损截图

UIView的无损截图

说明

1. 烂大街的代码

2. 写成category后，方便直接从drawRect中获取绘制出来的图片

3. 可以直接绘制图片供按钮设置背景图片用

4. 无损截图（包括alpha通道值也被无损保存）

源码

//
//  UIView+ScreensShot.h
//  ColorfulView
//
//  Created by YouXianMing on 15/7/17.
//  Copyright (c) 2015年 YouXianMing. All rights reserved.
//
 
#import <UIKit/UIKit.h>
 
@interface UIView (ScreensShot)
 
/**
 *  无损截图
 *
 *  This function may be called from any thread of your app.
 *
 *  @return 返回生成的图片
 */
- (UIImage *)screenShot;
 
@end

//
//  UIView+ScreensShot.m
//  ColorfulView
//
//  Created by YouXianMing on 15/7/17.
//  Copyright (c) 2015年 YouXianMing. All rights reserved.
//
 
#import "UIView+ScreensShot.h"
#import <objc/runtime.h>
 
@implementation UIView (ScreensShot)
 
- (UIImage *)screenShot {
 
    if (self && self.frame.size.height && self.frame.size.width) {
 
        UIGraphicsBeginImageContextWithOptions(self.frame.size, NO, );
        [self.layer renderInContext:UIGraphicsGetCurrentContext()];
        UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();
 
        return image;
 
    } else {
 
        return nil;
    }
 
}
 
@end

//
//  ViewController.m
//  ColorfulView
//
//  Created by YouXianMing on 15/7/10.
//  Copyright (c) 2015年 YouXianMing. All rights reserved.
//
 
#import "ViewController.h"
#import "UIView+ScreensShot.h"
 
@interface ViewController ()
 
@end
 
@implementation ViewController
 
- (void)viewDidLoad {
    [super viewDidLoad];
 
    self.view.backgroundColor = [UIColor blackColor];
 
    UIView *cyanView         = [[UIView alloc] initWithFrame:CGRectMake(, , , )];
    cyanView.backgroundColor = [UIColor cyanColor];
    cyanView.alpha           = 0.5f;
    [self.view addSubview:cyanView];
 
    UIImageView *imageView   = [[UIImageView alloc] initWithImage:[cyanView screenShot]];
    imageView.frame          = CGRectMake(, , , );
    [self.view addSubview:imageView];
}
 
@end