截屏 或 截取某个view的界面（给view拍照）

基本原理就是主要将UIView的layer描绘到图形上下文。UIView全局拍照和局域拍照的代码如下：

1 UIView全局拍照

[cpp] view plaincopy

1. - (UIImage *) screenImage:(UIView *)view {  
2. UIImage *screenImage;  
3. UIGraphicsBeginImageContext(view.frame.size);  
4. [view.layer renderInContext:UIGraphicsGetCurrentContext()];  
5. screenImage = UIGraphicsGetImageFromCurrentImageContext();  
6. UIGraphicsEndImageContext();  
7. return screenImage;  
8. }  

2 UIView局域拍照

[cpp] view plaincopy

1. - (UIImage *) screenImage:(UIView *)view rect:(CGRect)rect {  
2. CGPoint pt = rect.origin;  
3. UIImage *screenImage;  
4. UIGraphicsBeginImageContext(rect.size);  
5. CGContextRef context = UIGraphicsGetCurrentContext();  
6. CGContextConcatCTM(context,  
7. CGAffineTransformMakeTranslation(-(int)pt.x, -(int)pt.y));  
8. [view.layer renderInContext:context];  
9. screenImage = UIGraphicsGetImageFromCurrentImageContext();  
10. UIGraphicsEndImageContext();  
11. return screenImage;  
12. }  

截屏

[cpp] view plaincopy

1. UIGraphicsBeginImageContext(self.window.bounds.size);  
2. [self.window.layer renderInContext:UIGraphicsGetCurrentContext()];  
3. UIImage *image = UIGraphicsGetImageFromCurrentImageContext();  
4. UIGraphicsEndImageContext();  

保存为图片

[cpp] view plaincopy

1. NSData * data = UIImagePNGRepresentation(image);  
2.   
3.     if ([UIImagePNGRepresentation(viewImage) writeToFile:path atomically:YES])  
4.     {  
5.         NSLog(@"Succeeded!");  
6.         NSLog(@"%@",path);  
7.     }  
8.     else  
9.     {  
10.         NSLog(@"Failed!");  
11.     }