KVO實現自定義文件復制進度展示

2019-11-14 19:21:08

字體：大中小

來源：轉載

供稿：網友

一、創建文件

　　說明：自定義文件類，通過NSFileManager 以及NSFileHandle 實現文件的創建和copy,為了控制內存的并發使用，通過控制每次賦值的固定長度來分多次復制：

NSString * path=NSHomeDirectory();    path =[path stringByAppendingPathComponent:@"deskTop/Boby.m"];        NSString * target=NSHomeDirectory();    target =[target stringByAppendingPathComponent:@"deskTop/target.m"];        NSFileManager * manager=[NSFileManager defaultManager];            //校驗并且創建文件    if(![manager fileExistsAtPath:path]){        [manager createFileAtPath:path contents:nil attributes:nil];    }        if(![manager fileExistsAtPath:target]){        [manager createFileAtPath:target contents:nil attributes:nil];    }    NSDictionary * dic=[manager attributesOfItemAtPath:path error:nil];        NSFileHandle * handle=[NSFileHandle fileHandleForReadingAtPath:path];    NSFileHandle * handletTarget=[NSFileHandle fileHandleForWritingAtPath:target];        int total=(int)[dic[@"NSFileSize"] integerValue];    self.totalSize=total;    int per=50;    int count=total%per==0?total/per:total/per+1;    for(int i=0;i<count;i++){               [handle seekToFileOffset:self.nowSize];        NSData *data= [handle readDataOfLength:per];                int tem=per*(i+1);        if(tem>total){            tem=total;        }        self.nowSize=tem;         [handletTarget seekToEndOfFile];        [handletTarget writeData:data];        [NSThread sleepForTimeInterval:0.2];            }        [handle closeFile];[handletTarget closeFile];

二、設置觀察者

　　說明：自定義使用者，通過設置觀察者來動態觀察當前文件copy的進度并展示到控制臺或者輸出到UI，并提供方法接口，啟動文件拷貝。

- (id) initWithFile:(FileMake *)files{    self=[super init];        if(self){        self.file= files;        [self.file addObserver:self forKeyPath:@"nowSize" options:NSKeyValueObservingOptionNew context:nil];    }    return self;}-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context{    CGFloat all=self.file.totalSize;    CGFloat now=[[change objectForKey:@"new"] floatValue];    CGFloat result=now/all;     NSLog(@"%.2f",result);    //一定不能忘了銷毀當前的觀察者    if(result==1){        [self.file removeObserver:self forKeyPath:@"nowSize"];    }}- (void) begin{    [self.file startCopy];}