ios关于手机拨打电话，回调问题

需要导入下面两个头文件,导入CoreTelephony.framework，

#import "TelViewController.h"
#import <CoreTelephony/CTCallCenter.h>
#import <CoreTelephony/CTCall.h>

@interface TelViewController () 

@property (nonatomic, strong) CTCallCenter *callCenter;
@end

以下两种打电话的方式：

1.通常的方法
- (IBAction)phoneAction:(id)sender {
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"tel://10086"]];
}
2.获取回调的方法
- (IBAction)phoneWebAction:(id)sender {
    UIWebView *callWebview =[[UIWebView alloc] init] ;
 NSURL *telURL =[NSURL URLWithString:@"tel://514091"];
 [callWebview loadRequest:[NSURLRequest requestWithURL:telURL]];
    [self.view addSubview:callWebview];
}

处理回调

-(void)detectCall
{
        CTCallCenter *callCenter = [[CTCallCenter alloc] init];  
        callCenter.callEventHandler = ^(CTCall* call) {  
if ([call.callState isEqualToString:CTCallStateDisconnected])  
            {  
NSLog(@"挂断了电话咯Call has been disconnected");  
            }  
else if ([call.callState isEqualToString:CTCallStateConnected])  
            {  
NSLog(@"电话通了Call has just been connected");  
            }  
else if([call.callState isEqualToString:CTCallStateIncoming])  
            {  
NSLog(@"来电话了Call is incoming");  

            }  
else if ([call.callState isEqualToString:CTCallStateDialing])  
            {  
NSLog(@"正在拨出电话call is dialing");  
            }  
else    
            {    
NSLog(@"什么也没做Nothing is done");  
            }    
        };  
}