中文转码

str = [str stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

图片编码

NSData *data;

NSData -->UIImage

UIImage *image = [UIImage imageWithData:data];

UIImage-->NSData

NSData *data1 = UIImagePNGRepresentation(image);

NSData *data2 = UIImageJPEGRepresentation(image, 1.0);

NSData -->NSString

str = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];

NSString --> NSData

NSData *strData  = [str dataUsingEncoding:NSUTF8StringEncoding];