我的代码在普通设备上工作正常，但在视网膜设备上产生模糊的图像。
有人知道我的问题的解决方案吗?
+ (UIImage *) imageWithView:(UIView *)view
{
UIGraphicsBeginImageContext(view.bounds.size);
[view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage * img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return img;
}
当前回答
插入式Swift 3.0扩展，支持新的iOS 10.0 API和以前的方法。
注意:
iOS版本检查 注意使用defer来简化上下文清理。 还将应用视图的不透明度和当前比例。 没有任何东西只是使用!这可能会导致坠机。
extension UIView
{
public func renderToImage(afterScreenUpdates: Bool = false) -> UIImage?
{
if #available(iOS 10.0, *)
{
let rendererFormat = UIGraphicsImageRendererFormat.default()
rendererFormat.scale = self.layer.contentsScale
rendererFormat.opaque = self.isOpaque
let renderer = UIGraphicsImageRenderer(size: self.bounds.size, format: rendererFormat)
return
renderer.image
{
_ in
self.drawHierarchy(in: self.bounds, afterScreenUpdates: afterScreenUpdates)
}
}
else
{
UIGraphicsBeginImageContextWithOptions(self.bounds.size, self.isOpaque, self.layer.contentsScale)
defer
{
UIGraphicsEndImageContext()
}
self.drawHierarchy(in: self.bounds, afterScreenUpdates: afterScreenUpdates)
return UIGraphicsGetImageFromCurrentImageContext()
}
}
}
其他回答
我已经创建了一个基于@Dima解决方案的Swift扩展:
extension UIImage {
class func imageWithView(view: UIView) -> UIImage {
UIGraphicsBeginImageContextWithOptions(view.bounds.size, view.opaque, 0.0)
view.drawViewHierarchyInRect(view.bounds, afterScreenUpdates: true)
let img = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return img
}
}
编辑:Swift 4改进版本
extension UIImage {
class func imageWithView(_ view: UIView) -> UIImage {
UIGraphicsBeginImageContextWithOptions(view.bounds.size, view.isOpaque, 0)
defer { UIGraphicsEndImageContext() }
view.drawHierarchy(in: view.bounds, afterScreenUpdates: true)
return UIGraphicsGetImageFromCurrentImageContext() ?? UIImage()
}
}
用法:
let view = UIView(frame: CGRect(x: 0, y: 0, width: 100, height: 100))
let image = UIImage.imageWithView(view)
目前接受的答案已经过时了，至少如果你支持iOS 7的话。
如果你只支持iOS7+，下面是你应该使用的:
+ (UIImage *) imageWithView:(UIView *)view
{
UIGraphicsBeginImageContextWithOptions(view.bounds.size, view.opaque, 0.0f);
[view drawViewHierarchyInRect:view.bounds afterScreenUpdates:NO];
UIImage * snapshotImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return snapshotImage;
}
斯威夫特4:
func imageWithView(view: UIView) -> UIImage? {
UIGraphicsBeginImageContextWithOptions(view.bounds.size, view.isOpaque, 0.0)
defer { UIGraphicsEndImageContext() }
view.drawHierarchy(in: view.bounds, afterScreenUpdates: true)
return UIGraphicsGetImageFromCurrentImageContext()
}
根据这篇文章，你可以看到新的iOS7方法drawviewherarchyinrect:afterScreenUpdates:比renderInContext:快很多倍。
使用现代的uigraphicsimagerender
public extension UIView {
@available(iOS 10.0, *)
public func renderToImage(afterScreenUpdates: Bool = false) -> UIImage {
let rendererFormat = UIGraphicsImageRendererFormat.default()
rendererFormat.opaque = isOpaque
let renderer = UIGraphicsImageRenderer(size: bounds.size, format: rendererFormat)
let snapshotImage = renderer.image { _ in
drawHierarchy(in: bounds, afterScreenUpdates: afterScreenUpdates)
}
return snapshotImage
}
}
斯威夫特3
带有UIView扩展的Swift 3解决方案(基于Dima的回答)应该是这样的:
extension UIView {
public func getSnapshotImage() -> UIImage {
UIGraphicsBeginImageContextWithOptions(self.bounds.size, self.isOpaque, 0)
self.drawHierarchy(in: self.bounds, afterScreenUpdates: false)
let snapshotImage: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
UIGraphicsEndImageContext()
return snapshotImage
}
}
Swift 3.0实现
extension UIView {
func getSnapshotImage() -> UIImage {
UIGraphicsBeginImageContextWithOptions(bounds.size, isOpaque, 0)
drawHierarchy(in: bounds, afterScreenUpdates: false)
let snapshotImage = UIGraphicsGetImageFromCurrentImageContext()!
UIGraphicsEndImageContext()
return snapshotImage
}
}
