我正在根据本教程 ( http://bit.ly/NI9kQe ) 构建一个应用程序，它使用自定义 web api 连接到 web 服务器。要求之一是检测是否已点击登录或注册按钮。这是使用为界面生成器中的按钮设置的“标签”完成的（注册按钮的标签为 1）。
代码块位于 btnLoginRegisterTapped 方法中，如下所示（错误发生在行 -> NSString* command = (sender.tag==1)?@"register":@"login";）：
- (IBAction)btnLoginRegisterTapped:(id)sender {
//form fields validation
if (fldUserName.text.length < 4 || fldPassword.text.length < 4) {
// [UIAlertView error:@"Enter username and password over 4 chars each."];
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Opps!!" message:@"Enter username and password over 4 chars each." delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles:nil];
// optional - add more buttons:
[alert addButtonWithTitle:@"Yes"];
[alert show];
return;
}
//salt the password
NSString* saltedPassword = [NSString stringWithFormat:@"%@%@", fldPassword.text, kSalt];
//prepare the hashed storage
NSString* hashedPassword = nil;
unsigned char hashedPasswordData[CC_SHA1_DIGEST_LENGTH];
//hash the pass
NSData *data = [saltedPassword dataUsingEncoding: NSUTF8StringEncoding];
if (CC_SHA1([data bytes], [data length], hashedPasswordData)) {
hashedPassword = [[NSString alloc] initWithBytes:hashedPasswordData length:sizeof(hashedPasswordData) encoding:NSASCIIStringEncoding];
} else {
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Opps!!" message:@"Password cannot be reset!" delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles:nil];
// optional - add more buttons:
[alert addButtonWithTitle:@"Yes"];
[alert show];
return;
}
//************ THIS IS WHERE THE ERROR OCCURS *****************//
//check whether it's a login or register
NSString* command = (sender.tag==1)?@"register":@"login";
NSMutableDictionary* params =[NSMutableDictionary dictionaryWithObjectsAndKeys:
command, @"command",
fldUserName.text, @"username",
hashedPassword, @"password",
nil];
//make the call to the web API
[[API sharedInstance] commandWithParams:params
onCompletion:^(NSDictionary *json) {
//handle the response
//result returned
NSDictionary* res = [[json objectForKey:@"result"] objectAtIndex:0];
if ([json objectForKey:@"error"]==nil && [[res objectForKey:@"IdUser"] intValue]>0) {
//success
[[API sharedInstance] setUser: res];
[self.presentingViewController dismissViewControllerAnimated:YES completion:nil];
//show message to the user
[[[UIAlertView alloc] initWithTitle:@"Logged in"
message:[NSString stringWithFormat:@"Welcome %@",[res objectForKey:@"username"] ]
delegate:nil
cancelButtonTitle:@"Close"
otherButtonTitles: nil] show];
} else {
//error
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Opps!!" message:@"Server down? Try Again" delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles:nil];
// optional - add more buttons:
[alert addButtonWithTitle:@"Yes"];
[alert show];
return;
}
}];
}
当我尝试构建项目（实际上是工作区）时，出现错误：
在“_strong id”类型的对象上找不到属性“标签”
我正在使用为 iOS7 部署的 xcode 5.0。
谢谢，
