NSData dataWithContentsOfURL

Question

我有这个按钮点击（下载）的方法。问题是它由于异常而终止：

[Session started at 2011-03-14 13:06:45 +0530.]
2011-03-14 13:06:45.710 XML[7079:20b] *** Terminating app due to uncaught exception 'NSInvalidArgumentException',
reason: '*** -[NSCFString isFileURL]: unrecognized selector sent to instance 0x62b8'

-(IBAction) download
{
    UIImage *image = [UIImage imageWithData: [NSData dataWithContentsOfURL:@"http://ws.cdyne.com/WeatherWS/Images/thunderstorms.gif"]];
    [image release];
}

问题是什么？

Answer 1

它需要 NSURL 作为参数，而不是字符串。

UIImage *image = [UIImage imageWithData: [NSData dataWithContentsOfURL: [NSURL URLWithString:@"http://ws.cdyne.com/WeatherWS/Images/thunderstorms.gif"]]];

---

编辑：

要测试数据是否已成功加载，请尝试类似的操作

NSError* error = nil;
NSData* data = [NSData dataWithContentsOfURL:yourURL options:NSDataReadingUncached error:&error];
if (error) {
    NSLog(@"%@", [error localizedDescription]);
    [error release];
} else {
    NSLog(@"Data has loaded successfully.");
}

Answer 2

dataWithContentsOfURL 方法采用 NSURL 作为参数，而不是 NSString

[NSData dataWithContentsOfURL:[NSURL URLWithString:@"http://ws.cdyne.com/WeatherWS/Images/thunderstorms.gif"]]