iphone - 为什么没有performSelectorOnMainThread : in NSObject Protocol?

Question

最近我在开发应用程序。 iPhone(iOS) 项目。

我想知道为什么 NSObject 协议(protocol)中没有 performSelectorOnMainThread:。

我需要在主线程上调用委托(delegate)的方法，因为它们必须处理 UI 组件。

这是我写的示例:

@protocol MyOperationDelegate;

@interface MyOperation : NSOperation {
     id <MyOperationDelegate> delegate;
}
@property (nonatomic, assign) id <MyOperationDelegate> delegate;
@end

@protocol MyOperationDelegate <NSObject>
@optional
- (void) didFinishHandleWithResult:(NSDictionary *)result;
@end

@implementation MyOperation
@synthesize delegate;
- (void) main {
     NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

     NSDictionary *aDict = [[MySingleton sharedObject] fetchSomethingMeaningful];

     //do something and call delegate
     if ([delegate respondsToSelector:@selector(didFinishHandleWithResult:)]) {
          [delegate performSelector:@selector(didFinishHandleWithResult:) withObject:
     }

     [pool release];
}
@end


@interface MyViewCon : UIViewController <MyOperationDelegate> {
    NSOperationQueue *queue;
}
@end

@implementation MyViewCon
- (void) viewDidLoad {
    MyOperation *op = [[MyOperation alloc] init];
    op.delegate = self;
    [queue addOperation:op];
    [op release];
}

- (void) reloadUserInterface:(NSDictionary *)dict {
    // Do reload data on User Interfaces.
}

- (void) didFinishHandleWithResult:(NSDictionary *)myDict {
    // Couldn't execute method that's handling UI, maybe could but very slow...
    // So it must run on main thread.
    [self performSelectorOnMainThread:@selector(reloadUserInterface:) withObject:myDict];
}
@end

我可以在 MyOperation 类的主线程上运行 didFinishHandleWithResult: delegate 方法吗？

从这里开始，我每次调用 MyOperation 实例时都会实现 UI 处理方法。任何建议都会对我有所帮助。

Answer 1

让我们试试:

dispatch_async(dispatch_get_main_queue(), ^{

        //your main thread code here

    });