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今天在使用协议的过程中,偶然发现这样使用
@interface AppDelegate (){
id<ChatDelegate> testdelegate;
}
@property (nonatomic , assign) id<ChatDelegate> testdelegate;
@end
@implementation AppDelegate
@synthesize testdelegate;
会报错:
Existing instance variable 'delegate' for property 'delegate' with assign attribute must be unsafe unretained
修改成:
@interface AppDelegate (){
__unsafe_unretained id<ChatDelegate> testdelegate;
}
@property (nonatomic , assign) id<ChatDelegate> testdelegate;
@end
@implementation AppDelegate
@synthesize testdelegate;
就好了,这只是为了相容iOS4以下的版本
参考:http://www.cnblogs.com/lyanet/archive/2013/05/07/3064290.html