本文实例为大家分享了KVO实现自定义文件复制进度展示的具体代码,供大家参考,具体内容如下
一、创建文件
说明:自定义文件类,通过NSFileManager 以及NSFileHandle 实现文件的创建和copy,为了控制内存的并发使用,通过控制每次赋值的固定长度来分多次复制:
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NSString * path=NSHomeDirectory();
path =[path stringByAppendingPathComponent:@ "deskTop/Boby.m" ];
NSString * target=NSHomeDirectory();
target =[target stringByAppendingPathComponent:@ "deskTop/target.m" ];
NSFileManager * manager=[NSFileManager defaultManager];
//校验并且创建文件
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];
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二、设置观察者
说明:自定义使用者,通过设置观察者来动态观察当前文件copy的进度并展示到控制台或者输出到UI,并提供方法接口,启动文件拷贝。
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- (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);
//一定不能忘了销毁当前的观察者
if (result==1){
[self.file removeObserver:self forKeyPath:@ "nowSize" ];
}
}
- ( void ) begin{
[self.file startCopy];
}
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以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持服务器之家。
原文链接:http://www.cnblogs.com/jerehedu/p/4377162.html