ios - 如何使 imageView 固定大小并带有圆角

Question

我正在使用 Parse.com 构建一个简单的应用程序。我想知道是否有任何方法可以使 imageView 大小固定(例如 30x30px)并使图像的角变圆？

   - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
    //-------------------------------------------------------------------------------------------------------------------------------------------------
    {
        PFTableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"cell"];
        if (cell == nil) cell = [[PFTableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:@"cell"];

        PFUser *user = users[indexPath.row];
        cell.textLabel.text = user[PF_USER_FULLNAME];

        PFImageView *imageView = [[PFImageView alloc]  init];
        [imageView setBackgroundColor:[UIColor clearColor]];
        cell.imageView.image = [UIImage imageNamed:@"tab_profile.png"]; // placeholder image

        cell.imageView.file = (PFFile *)user[PF_USER_THUMBNAIL]; // remote image

        [cell.imageView loadInBackground];

        return cell;
    }

请提供任何建议，我是 Xcode 和 Parse SDK 的新手...

1)

2)

Answer 1

这是我通常用来在 imageView 上获得圆圈的方法:

1. 裁剪(而不是调整大小)图像以使其成为正方形。下面的方法将图像的大小调整为您作为 CGSize 传递的任何大小:

   (UIImage *)squareImageWithImage:(UIImage *)image scaledToSize:(CGSize)newSize
   {
       double ratio;
       double delta;
       CGPoint offset;
   
       //make a new square size, that is the resized imaged width
       CGSize sz = CGSizeMake(newSize.width, newSize.width);
   
       //figure out if the picture is landscape or portrait, then
       //calculate scale factor and offset
       if (image.size.width > image.size.height)
       {
           ratio = newSize.width / image.size.width;
           delta = (ratio*image.size.width - ratio*image.size.height);
           offset = CGPointMake(delta/2, 0);
       } else {
           ratio = newSize.width / image.size.height;
           delta = (ratio*image.size.height - ratio*image.size.width);
           offset = CGPointMake(0, delta/2);
       }
   
       //make the final clipping rect based on the calculated values
       CGRect clipRect = CGRectMake(-offset.x, -offset.y,
                            (ratio * image.size.width) + delta,
                            (ratio * image.size.height) + delta);
   
   
       //start a new context, with scale factor 0.0 so retina displays get
       //high quality image
       if ([[UIScreen mainScreen] respondsToSelector:@selector(scale)]) {
           UIGraphicsBeginImageContextWithOptions(sz, YES, 0.0);
       } else {
           UIGraphicsBeginImageContext(sz);
       }
       UIRectClip(clipRect);
       [image drawInRect:clipRect];
       UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
       UIGraphicsEndImageContext();
   
       return newImage;
   }
   

然后，调用刚刚创建的方法，并应用角半径(在本例中它将是一个圆):

imageView.image = [self squareImageWithImage:imageNormal scaledToSize:CGSizeMake(50, 50)]; // assuming you want a 50x50px image
// convert imageview to circle
imageView.layer.cornerRadius = cell.imageView.frame.size.width / 2;
imageView.clipsToBounds = YES;

您可以使用相同的调用将 cornerRadius 的数量减少到其他值。