将图片下载到系统相册里

在.h文件里写入:
voidUIImageWriteToSavedPhotosAlbum(

UIImage*image,

id completionTarget,

SEL completionSelector,

void
*contextInfo
);

#pragma mark IOS的UIKit Framework提供了UIImageWriteToSavedPhotosAlbum方法对图像进行保存，该方法会将image保存至用户的相册中
//参数1. image:带保存的图片UIImage对象

//参数2. completionTarget:图像保存至相册后调用completionTarget指定的selector(可选)

//参数3. completionSelector:completionTarget的方法对应的选择器，相当于回调方法，需满足以下格式

/*

- (void) image: (UIImage *) image

didFinishSavingWithError: (NSError *) error

contextInfo: (void *) contextInfo;

*/
// contextInfo指定了在回调中可选择传入的数据

在.m文件里写入:
一.在 viewDidLoad里写入
//要保存的图片
UIImage*saveImage = [UIImageimageNamed:@"6.JPG"];

//保存图片到相册中
[selfsaveImageToPhotos:saveImage];

- (void)saveImageToPhotos:(UIImage*)savedImage

{

UIImageWriteToSavedPhotosAlbum(savedImage,self,@selector(image:didFinishSavingWithError:contextInfo:),nil);

}

- (void)image:(UIImage*)image didFinishSavingWithError:(NSError*)error

contextInfo:(void*)contextInfo

{

NSString
*msg = nil;

if
(error != NULL) {

msg = @"保存图片失败";

}else{

msg = @"保存图片成功";

}

UIAlertView*alert = [[UIAlertViewalloc]initWithTitle:@"保存图片结果提示"message:msgdelegate:selfcancelButtonTitle:@"确定"otherButtonTitles:nil];

[alert show];
}