根據size截取螢幕中間矩形地區，size截取螢幕矩形

根據size截取螢幕中間矩形地區，size截取螢幕矩形

代碼：

- (void)viewDidLoad{    [super viewDidLoad];    // Do any additional setup after loading the view.        UIImageView *imageView=[[UIImageView alloc]initWithFrame:CGRectMake(50, 100, 200, 200)];    imageView.backgroundColor=[UIColor redColor];    //顯示截取的圖    imageView.image=[self cutCenterImage:[UIImage imageNamed:@"1.jpg"] size:CGSizeMake(200, 200)];    [self.view addSubview:imageView];        }#pragma mark 根據size截取圖片中間矩形地區的圖片 這裡的size是正方形-(UIImage *)cutCenterImage:(UIImage *)image size:(CGSize)size{    CGSize imageSize = image.size;    CGRect rect;    //根據圖片的大小計算出圖片中間矩形地區的位置與大小    if (imageSize.width > imageSize.height) {        float leftMargin = (imageSize.width - imageSize.height) * 0.5;        rect = CGRectMake(leftMargin, 0, imageSize.height, imageSize.height);    }else{        float topMargin = (imageSize.height - imageSize.width) * 0.5;        rect = CGRectMake(0, topMargin, imageSize.width, imageSize.width);    }        CGImageRef imageRef = image.CGImage;    //截取中間地區矩形圖片    CGImageRef imageRefRect = CGImageCreateWithImageInRect(imageRef, rect);        UIImage *tmp = [[UIImage alloc] initWithCGImage:imageRefRect];    CGImageRelease(imageRefRect);        UIGraphicsBeginImageContext(size);    CGRect rectDraw = CGRectMake(0, 0, size.width, size.height);    [tmp drawInRect:rectDraw];    // 從當前context中建立一個改變大小後的圖片    tmp = UIGraphicsGetImageFromCurrentImageContext();        // 使當前的context出堆棧    UIGraphicsEndImageContext();        return tmp;}