ios 转图片

 1 //转图片
 2 - (BOOL)imageHasAlpha: (UIImage *) image
 3 {
 4     CGImageAlphaInfo alpha = CGImageGetAlphaInfo(image.CGImage);
 5     return (alpha == kCGImageAlphaFirst ||
 6             alpha == kCGImageAlphaLast ||
 7             alpha == kCGImageAlphaPremultipliedFirst ||
 8             alpha == kCGImageAlphaPremultipliedLast);
 9 }
10 - (NSString *) image2DataURL: (UIImage *) image
11 {
12 
13     NSData *imageData = nil;
14     NSString *mimeType = nil;
15     
16     if ([self imageHasAlpha: image]) {
17         imageData = UIImagePNGRepresentation(image);
18         mimeType = @"image/png";
19     } else {
20         imageData = UIImageJPEGRepresentation(image, 1.0f);
21         mimeType = @"image/jpeg";
22     }
23     
24     
25     return [imageData base64EncodedStringWithOptions: 0];
26     
27 }