iOS 模仿蘋果編寫單例
阿新 • • 發佈：2017-06-24
調用 with void obj can nal lin elf enc
#import <Foundation/Foundation.h>
@interface Person : NSObject
+(instancetype)sharePerson;
@end
#import "Person.h"
@implementation Person
static Person *_instance = nil;
+(void)load{
_instance = [[self alloc] init];// 已進入就調用
}
+(instancetype)sharePerson{
return _instance;
}
+(instancetype)alloc{
if (_instance) { // 禁止調用alloc
NSException *exception = [NSException exceptionWithName:NSInternalInconsistencyException reason:@"There can only be on Person instance" userInfo:@{}];
[exception raise];// 拋出異常
}
return [super alloc];
}
@end
iOS 模仿蘋果編寫單例