UIImage转NSData，NSData转UIImage

1  UIImage转NSData

UIImage *image= [UIImage imageWithData:data];

带比例：

UIImage *image = [UIImageimageWithData:data scale:1.0];

1  NSData转UIImage

NSData *data;

if (UIImagePNGRepresentation(img) ==nil) {

    data = UIImageJPEGRepresentation(img,1.0);

}else{

    data = UIImagePNGRepresentation(img);

}