关于UIImage的一些拓展

#import <Foundation/Foundation.h>

@interface UIImage (MyImage)

+ (UIImage*)imageFromView:(UIView*)view;

+ (UIImage*)imageFromView:(UIView*)view scaledToSize:(CGSize)newSize;

+ (UIImage*)imageWithImage:(UIImage*)image scaledToSize:(CGSize)newSize;

@end

使用如下方法可以方便的对已加载的view截图，主要用于缩略图的显示。

#import "MyImage.h"

@implementation UIImage (MyImage)

+ (void)beginImageContextWithSize:(CGSize)size

{

    if ([[UIScreen mainScreen] respondsToSelector:@selector(scale)]) {

        if ([[UIScreen mainScreen] scale] == 2.0) {

            UIGraphicsBeginImageContextWithOptions(size, NO, 2.0);

        } else {

            UIGraphicsBeginImageContext(size);

        }

    } else {

        UIGraphicsBeginImageContext(size);

    }

}

+ (void)endImageContext

{

    UIGraphicsEndImageContext();

}

+ (UIImage*)imageFromView:(UIView*)view

{

    [self beginImageContextWithSize:[view bounds].size];

    BOOL hidden = [view isHidden];

    [view setHidden:NO];

    [[view layer] renderInContext:UIGraphicsGetCurrentContext()];

    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();

    [self endImageContext];

    [view setHidden:hidden];

    return image;

}

+ (UIImage*)imageFromView:(UIView*)view scaledToSize:(CGSize)newSize

{

    UIImage *image = [self imageFromView:view];

    if ([view bounds].size.width != newSize.width ||

        [view bounds].size.height != newSize.height) {

        image = [self imageWithImage:image scaledToSize:newSize];

    }

    return image;

}

+ (UIImage*)imageWithImage:(UIImage*)image scaledToSize:(CGSize)newSize

{

    [self beginImageContextWithSize:newSize];

    [image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];

    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();

    [self endImageContext];

    return newImage;

}

@end