iOS从URL加载图像
[英]iOS Loading an Image from a URL
问题描述
I am experiencing some issues when I load a UIImage from a URL into a UIImageView on the iPhone. 
当我从URL将UIImage加载到iPhone上的UIImageView时遇到一些问题。 When I generate the NSURL (with the URL in the argument of NSURL's URLWithString method) using properties of an object, the image is not retrieved at all, however if I hardcode the same URL, the image is retrieved and displayed as expected. 当我使用对象的属性生成NSURL（在NSURL的URLWithString方法的参数中带有URL）时，根本不会检索图像，但是，如果我对相同的URL进行硬编码，则会按预期检索并显示图像。
The [item valueForKey:@"pictureLocation"]; [item valueForKey：@“ pictureLocation”]; part below seems to be what is causing the problem because even when two hardcoded strings are concatenated, the NSURl is generated with no issues. 下面的部分似乎是导致问题的原因，因为即使将两个硬编码的字符串连接在一起，NSURl的生成也没有问题。
NSString * imagePath = @"http://localhost:3000";
NSString * specificPath = (NSString *)[item valueForKey:@"pictureLocation"] ;
//concatenate the strings to get a fully formed URL
NSString * finalPath = [imagePath stringByAppendingString:specificPath];
UIImage *img = [[UIImage imageWithData: [NSData dataWithContentsOfURL: [NSURL URLWithString:finalPath]]] retain];
Essentially, when I NSLog the finalPath and instead hardcode that URL into the program, I get the expected result. 本质上，当我NSLog the finalPath并将该URL硬编码到程序中时，我得到了预期的结果。
Why this might be the case? 为什么会这样呢？
3 个解决方案
解决方案1
0 2009-08-18 05:29:20
How is the NSString returned by valueForKey: formed? valueForKey:返回的NSString是如何形成的？ Is it something like "image.png", or is it "/image.png"? 是“ image.png”还是“ /image.png”？ If it's the former, you'll want to use stringByAppendingPathComponent: instead of stringByAppendingString: . 如果是前者，则需要使用stringByAppendingPathComponent:而不是stringByAppendingString:
解决方案2
0 2009-08-18 05:45:06
You need to use the UIWebView and load a html <img /> inside it. 您需要使用UIWebView并在其中加载html <img /> 。 At least this is a nice workaround. 至少这是一个不错的解决方法。
Check the code here http://blog.timeister.com/2009/07/18/iphone-show-online-image/ 在此处检查代码http://blog.timeister.com/2009/07/18/iphone-show-online-image/
- (void)loadImage:(NSString*)url frame:(CGRect)frame {
NSString* textHTML = @"
<html><head>
<style type=\"text/css\">
body {
background-color: transparent;
color: white;
}
</style>
</head><body style=\"margin:0\">
<img src=\"%@\" width=\"%0.0f\" height=\"%0.0f\"></img>
</body></html>";
NSString* html = [NSString stringWithFormat:textHTML, url, frame.size.width, frame.size.height];
if(webView == nil) {
webView = [[UIWebView alloc] initWithFrame:frame];
[self.view addSubview:webView];
}
[webView loadHTMLString:html baseURL:nil];
}
Adrian 阿德里安
解决方案3
0 2010-01-27 06:13:30
I think problem is related to proper encoding. 我认为问题与正确的编码有关。
try encoding the parameters properly by using following function : 尝试使用以下函数对参数进行正确编码：
encodedparams = [params stringByAddingPercentEscapesUsingEncoding:NSASCIIStringEncoding];
So in your case : 因此，在您的情况下：
NSString * specificPath = (NSString *)[item valueForKey:@"pictureLocation"] ;
specificPath = [specificPath stringByAddingPercentEscapesUsingEncoding:NSASCIIStringEncoding];
I think this will solve your problem. 我认为这可以解决您的问题。
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