How to display a base64 image within a UIImageView?

问题:

I got this Base64 gif image:

R0lGODlhDAAMALMBAP8AAP///wAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAACH5BAUKAAEALAAAAAAMAAwAQAQZMMhJK7iY4p3nlZ8XgmNlnibXdVqolmhcRQA7 

Now I want to display this Base64 String within my IPhone App.

I could get this working by using the WebView:

aUIWebView.scalesPageToFit = NO; aUIWebView.opaque = NO; aUIWebView.backgroundColor = [UIColor clearColor];  [aUIWebView loadHTMLString:   @""  baseURL:nil]; 

Is it possible to do the same thing by using the UIImageView?

回答1:

You don't have to encode it. Simply make a NSUrl, it knows the "data:"-url.

NSURL *url = [NSURL URLWithString:base64String];     NSData *imageData = [NSData dataWithContentsOfURL:url]; UIImage *ret = [UIImage imageWithData:imageData]; 

As mentioned in the comments, you have to make sure that you prepend your data with data:image/png;base64, or else your base64 data is useless.

回答2:

Very old question, but as of iOS7 there is a new, much easier way to do so, hence I'm writing it here so future readers can use this.

NSData* data = [[NSData alloc] initWithBase64EncodedString:base64String options:0]; UIImage* image = [UIImage imageWithData:data]; 

Very easy to use, and will not hit the 2048 byte size limit of a URL.

回答3:

This Code will display an base64 encoded string as a picture:

NSString *str = @"data:image/jpg;base64,"; str = [str stringByAppendingString:restauInfo.picture]; NSData *imageData = [NSData dataWithContentsOfURL:[NSURL URLWithString:str]]; 

restauInfo.picture is an NSString which contains the base64 encoded JPG

In my case the Value from "restauInfo.picture" comes from a database

回答4:

You can do something like the following:

(UIImage *)decodeBase64ToImage:(NSString *)strEncodeData {   NSData *data = [[NSData alloc]initWithBase64EncodedString:strEncodeData options:NSDataBase64DecodingIgnoreUnknownCharacters];   return [UIImage imageWithData:data]; } 

Then call it like this:

UIImage *image = [self decodeBase64ToImage:dataString]; 

回答5:

1. Decode Base64 to raw binary. You're on your own here. You might find cStringUsingEncoding: of NSString useful.
2. Create NSData instance using dataWithBytes:length:
3. Use [UIImage imageWithData:] to load it.

回答6:

Thanks porneL

I could find a Base64 script using google: Base64.m

So I modified it a little bit and could get a working test code:

NSString * base64img = @"R0lGODlhDAAMALMBAP8AAP///wAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACH5BAUKAAEALAAAAAAMAAwAQAQZMMhJK7iY4p3nlZ8XgmNlnibXdVqolmhcRQA7"; base64Data = [base64img dataUsingEncoding:NSASCIIStringEncoding]; base64Bytes = [base64Data bytes]; mutableData = [NSMutableData dataWithCapacity:[base64Data length]]; lentext = [base64Data length];  while( YES ) {        if( ixtext >= lentext ) break;        ch = base64Bytes[ixtext++];        flignore = NO;         if( ( ch >= 'A' ) && ( ch = 'a' ) && ( ch = '0' ) && ( ch > 4 );             outbuf [1] = ( ( inbuf[1] & 0x0F ) > 2 );             outbuf [2] = ( ( inbuf[2] & 0x03 ) 

回答7:

Just in case anyone is looking for the Swift code to accomplish this (based on the Objective-C answer provided by Jonathan M), here it is:

var data = NSData (base64EncodedString: base64String, options: NSDataBase64DecodingOptions(0)) var image = UIImage(data: data!) 

回答8:

Objective-C

NSString *plainString = @"foo"; 

Encoding

NSData *plainData = [plainString dataUsingEncoding:NSUTF8StringEncoding]; NSString *base64String = [plainData base64EncodedStringWithOptions:0]; NSLog(@"%@", base64String);   

Decoding

NSData *decodedData = [[NSData alloc] initWithBase64EncodedString:base64String options:0]; NSString *decodedString = [[NSString alloc] initWithData:decodedData encoding:NSUTF8StringEncoding]; NSLog(@"%@", decodedString);  

Option

NSURL *URL = [NSURL URLWithString:   [NSString stringWithFormat:@"data:application/octet-stream;base64,%@",        base64String]];   return [NSData dataWithContentsOfURL:URL]; 

Swift

let plainString = "foo" 

Encoding

let plainData = (plainString as NSString).dataUsingEncoding(NSUTF8StringEncoding) let base64String = plainData.base64EncodedStringWithOptions(NSDataBase64EncodingOptions.fromRaw(0)!) println(base64String)  

Decoding

let decodedData = NSData(base64EncodedString: base64String, options: NSDataBase64DecodingOptions.fromRaw(0)!) let decodedString = NSString(data: decodedData, encoding: NSUTF8StringEncoding)     println(decodedString) // foo 

回答9:

In my case worked a solution proposed here by @Masche. As I needed it in Swift 2.0 so:

let url = NSURL(string: imageString) let data = NSData.init(contentsOfURL: url!) let image = UIImage(data: imageData) 

回答10:

Code snippet for downloading a text file with base64 image string inside, then saving/reading the file and finally creating an image to display right in the view

In Case You Need To Decode Image To Base64 Click Here

NSString *downloadUrl = "http://www.server.com/file.txt"; // NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString: downloadUrl]]; // // DOWNLOAD THE FILE // [NSURLConnection sendAsynchronousRequest:request queue:[NSOperationQueue currentQueue] completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {     if (error) {          NSLog(@"Download Error:%@",error.description);      }     if (data) {         [data writeToFile:filePath atomically:YES];         //         // PROCESS BASE 64 STRING         //         NSString * fileContents = [NSString stringWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:nil];         //         // PROCESS BASE 64 STRING         //         NSString *base64String = fileContents;         NSURL *url = [NSURL URLWithString:base64String];         NSData *imageData = [NSData dataWithContentsOfURL:url];         //         // CREATE IMAGE         //         UIImage *ret = [UIImage imageWithData:imageData];         self.myImage.image = ret;     } } 

文章来源: How to display a base64 image within a UIImageView?