同一個類有多個alertView, 不一樣的alertView 點擊肯定按鈕 執行的方法不一樣spa
alertOne 點擊 肯定按鈕 執行 methodOne, alertTwo 點擊肯定按鈕 執行 methodTwo代理
初始化並顯示 alertOne
code
- (IBAction)showAlertOne:(id)sender { UIAlertView *alertOne = [[UIAlertView alloc]initWithTitle:@"AlertOne" message:@"" delegate:self cancelButtonTitle:@"取消" otherButtonTitles:@"肯定", nil]; [alertOne setTag:1]; [alertOne show]; }
初始化並顯示alertTwoorm
- (IBAction)showAlertTwo:(id)sender { UIAlertView *alertTwo = [[UIAlertView alloc]initWithTitle:@"AlertTwo" message:@"" delegate:self cancelButtonTitle:@"取消" otherButtonTitles:@"肯定", nil]; [alertTwo setTag:2]; [alertTwo show]; }
實現代理對象
-(void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex { if (buttonIndex == 0) { return; } if (alertView.tag == 1) { if (buttonIndex == 1) { [self methodOne]; } } else if (alertView.tag == 2) { if (buttonIndex == 1) { [self methodTwo]; } } }
import runtime.h,定義屬性關聯keyci
#import "ViewController.h" #import <objc/runtime.h> static void *alertViewKey = "alertViewKey";
初始化並顯示 alertOne,同時定義block,將block 與 alertOne 關聯get
- (IBAction)showAlertOne:(id)sender { UIAlertView *alertOne = [[UIAlertView alloc]initWithTitle:@"AlertOne" message:@"" delegate:self cancelButtonTitle:@"取消" otherButtonTitles:@"肯定", nil]; void (^block)(NSInteger) = ^(NSInteger buttonIndex) { if (buttonIndex == 1) { [self methodOne]; } }; objc_setAssociatedObject(alertOne, alertViewKey, block, OBJC_ASSOCIATION_COPY);//將block 與 alertOne 關聯 [alertOne show];
初始化並顯示 alertTwo,同時定義block,將block 與 alertTwo 關聯it
- (IBAction)showAlertTwo:(id)sender { UIAlertView *alertTwo = [[UIAlertView alloc]initWithTitle:@"AlertTwo" message:@"" delegate:self cancelButtonTitle:@"取消" otherButtonTitles:@"肯定", nil]; void (^block)(NSInteger) = ^(NSInteger buttonIndex) { if (buttonIndex == 1) { [self methodTwo]; } }; objc_setAssociatedObject(alertTwo, alertViewKey, block, OBJC_ASSOCIATION_COPY); [alertTwo show]; }
實現代理,在代理方法中,直接取出當前alert 所關聯上的 block,再將buttonIndex 傳入,讓block 本身調用對應方法io
-(void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex { if (buttonIndex == 0) { return; } void(^block)(NSInteger) = objc_getAssociatedObject(alertView, alertViewKey); block(buttonIndex); }
經過使用Associated object 方法有多個好處 :class
簡化代碼
讓代碼層次清晰
充分利用對象與屬性的擁有關係