Add support for PNG compression on iOS (#43)

README.md

@@ -40,7 +40,7 @@ Option | Description
 path | Path of image
 maxWidth | Image max width (ratio is preserved)
 maxHeight | Image max height (ratio is preserved)
-compressFormat | Can be either JPEG, PNG (android only) or WEBP (android only).
+compressFormat | Can be either JPEG, PNG or WEBP (android only).
 quality | A number between 0 and 100. Used for the JPEG compression.
 rotation | Rotation to apply to the image, in degrees, for android only. On iOS, the resizing is done such that the orientation is always up.
 outputPath | The resized image path. If null, resized image will be stored in cache folder. To set outputPath make sure to add option for rotation too (if no rotation is needed, just set it to 0).

index.ios.js

@@ -4,12 +4,12 @@ import {
 
 export default {
   createResizedImage: (path, width, height, format, quality, rotation = 0, outputPath) => {
-    if (format !== 'JPEG') {
-      throw new Error('Only JPEG format is supported by createResizedImage');
+    if (format !== 'JPEG' && format !== 'PNG') {
+      throw new Error('Only JPEG and PNG format are supported by createResizedImage');
     }
 
     return new Promise((resolve, reject) => {
-      NativeModules.ImageResizer.createResizedImage(path, width, height, quality, outputPath, (err, resizedPath) => {
+      NativeModules.ImageResizer.createResizedImage(path, width, height, format, quality, outputPath, (err, resizedPath) => {
         if (err) {
           return reject(err);
         }

ios/RCTImageResizer/RCTImageResizer.m

@@ -15,11 +15,22 @@
 
 RCT_EXPORT_MODULE();
 
-void saveImage(NSString * fullPath, UIImage * image, float quality)
+bool saveImage(NSString * fullPath, UIImage * image, NSString * format, float quality)
 {
-    NSData* data = UIImageJPEGRepresentation(image, quality / 100.0);
+    NSData* data = nil;
+    if ([format isEqualToString:@"JPEG"]) {
+        data = UIImageJPEGRepresentation(image, quality / 100.0);
+    } else if ([format isEqualToString:@"PNG"]) {
+        data = UIImagePNGRepresentation(image);
+    }
+    
+    if (data == nil) {
+        return NO;
+    }
+    
     NSFileManager* fileManager = [NSFileManager defaultManager];
     [fileManager createFileAtPath:fullPath contents:data attributes:nil];
+    return YES;
 }
 
 NSString * generateFilePath(NSString * ext, NSString * outputPath)
@@ -43,6 +54,7 @@ NSString * generateFilePath(NSString * ext, NSString * outputPath)
 RCT_EXPORT_METHOD(createResizedImage:(NSString *)path
                   width:(float)width
                   height:(float)height
+                  format:(NSString *)format
                   quality:(float)quality
                   outputPath:(NSString *)outputPath
                   callback:(RCTResponseSenderBlock)callback)
@@ -71,7 +83,12 @@ RCT_EXPORT_METHOD(createResizedImage:(NSString *)path
             return;
         }
 
-        saveImage(fullPath, scaledImage, quality);
+        // Compress and save the image
+        if (!saveImage(fullPath, scaledImage, format, quality)) {
+            callback(@[@"Can't save the image. Check your compression format.", @""]);
+            return;
+        }
+        
         callback(@[[NSNull null], fullPath]);
     }];
 }