objective-c - 以字节为单位获取图像大小

Question

我有两种方法，都给出了错误的答案。

NSMutableArray *img=[[NSMutableArray alloc]init];
img=[memoInstance getTempImagesToSend]; //get nsmutableArray of images
NSData* myEncodedImageData=[img objectAtIndex:0];    
NSLog(@"IMAGE1:%@",[UIImage imageWithData:myEncodedImageData]); //i see image

NSLog(@"len:%lu",(unsigned long)[myEncodedImageData length]); //first way to show size

NSData *imgData = UIImageJPEGRepresentation([UIImage imageWithData:myEncodedImageData], 1);
NSLog(@"Size of Image(bytes):%d",[imgData length]); //second way to show

第一种方式：len:34898

第二种方式：Size of Image(bytes):47701

图片来自相册，用iphone拍的。它不能是 47k ......应该是 ±500k

Answer 1

尝试改变你的

NSData *imgData = UIImageJPEGRepresentation([UIImage imageWithData:myEncodedImageData], 1);

为了

NSData *imgData = [[NSData alloc] initWithData:UIImageJPEGRepresentation((your_ui_image), 0.5)];

Answer 2

尝试以下操作：

int height = image.size.height; int width = image.size.width; 
int bytesPerRow = 4*width; 

if (bytesPerRow % 16) 
bytesPerRow = ((bytesPerRow / 16) + 1) * 16; 

int dataSize = height*bytesPerRow;