protocol应用两个controller之间或者controller与自定义UIView之间的相互调用。
它的应用类似java或者C#里的interface。假设A调用B，B回调A，那么就可以如此设计：
首先：定义一个protocal:
@protocol PtlChart
@optional
-(void) callBack:(id)arg;
@required
-(void) loadData;
@end
第二步：在B里定义protocal的delegate：
//B.h
@interface B : UIView {
id<PtlChart> _delegate;
}
@property (nonatomic,retain) id<PtlChart> delegate;
@end
//B.m:
#import "B.h"
@implementation B
@synthesize delegate = _delegate;
- (void)dealloc {
[_delegate release];
}
@end
@interface B : UIView {
id<PtlChart> _delegate;
}
@property (nonatomic,retain) id<PtlChart> delegate;
@end
//B.m:
#import "B.h"
@implementation B
@synthesize delegate = _delegate;
- (void)dealloc {
[_delegate release];
}
@end
第三步：在A里调用B时，把delegate传递过去：
//A.h:
@interface A : UIViewController<PtlChart>
@end
//A.m:
#import "A.h"
@implementation A
- (void) loadData {
A *a = [[A alloc] init];
[a setDelegate:self]; //<<--------- here
[self.view addSubview:a];
[a release];
}
-(void) callBack:(id)arg{
int i = (int)arg;
NSLog(@"callback= %d",i);
}
@end
@interface A : UIViewController<PtlChart>
@end
//A.m:
#import "A.h"
@implementation A
- (void) loadData {
A *a = [[A alloc] init];
[a setDelegate:self]; //<<--------- here
[self.view addSubview:a];
[a release];
}
-(void) callBack:(id)arg{
int i = (int)arg;
NSLog(@"callback= %d",i);
}
@end