ios 图片的压缩分为两种:容量和尺寸
1.容量的压缩:
NSData *data = UIImageJPEGRepresentation(image, 0.5); //(图片, 压缩系数)
UIImage *newImage = [UIImage imageWithData: data];
2.尺寸的压缩:
CGSize size = CGSizeMake(100, 100);//压缩后的尺寸
UIGraphicsBeginImageContext(CGSizeMake(size.width, size.height)); //设置基于位图的上下文,并将其设为当前上下文
[image drawInRect:CGRectMake(0, 0, size.width, size.height)]; //将图片渲染到当前的上下文中
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext(); //获取当前上下文的图片
UIGraphicsEndImageContext(); //释放上下文