NSTimer定时器的简单用法/NSTimer Instance

NSTimer定时器的简单用法

版本信息：

OS version : 10.10
Interface Name: NSTimer
Location : Frameworks/Foundation/NSTimer.h

OC源码：

#import <Foundation/NSObject.h>

#import <Foundation/NSDate.h>

@interface NSTimer :NSObject
//类方法
+ (NSTimer *)scheduledTimerWithTimeInterval:(NSTimeInterval)ti target:(id)aTarget selector:(SEL)aSelector userInfo:(id)userInfo repeats:(BOOL)yesOrNo;

今天只关注上面的这个类方法，这个类方法很实用滴，（打印日志文件，纪录用户操作等等）。
以打印日志文件为例,需要用到3个文件：
Log.h

#import <Foundation/Foundation.h>

@interface Log : NSObject

- (void) Log;//for log

- (void) timerAction:(NSTimer *)timer;

@end

Log.m

#import "Log.h"

@implementation Log
- (void)Log
{

NSFileManager *fileManager = [NSFileManager defaultManager];
NSString *path = NSHomeDirectory();
NSString *filePath = [path stringByAppendingString:@"/IOS/Log.txt"];//create a txt file for log
BOOL success = [fileManager createFileAtPath:filePath contents:nil attributes:nil];
if (success) {
NSLog(@"create success");
}
//NSFileHandle for handle the txt file
NSFileHandle *fileHandle = [NSFileHandle fileHandleForWritingAtPath:filePath];
[NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(timerAction:) userInfo:fileHandle repeats:YES];
//NSTimer定时器使用，每一秒call一次timerAction,写入当前时间到txt file 里面
}
- (void) timerAction:(NSTimer *)timer
{
static int i = 0;

NSFileHandle *fileHandle = timer.userInfo;
[fileHandle seekToEndOfFile];

NSDate *now = [NSDate date];
NSDateFormatter *dateFormate = [[NSDateFormatter alloc] init];
[dateFormate setDateFormat:@" --- yyyy/MM/dd HH:mm:ss"];
NSString *dateNowString = [dateFormate stringFromDate:now];
dateNowString = [dateNowString stringByAppendingString:@"\n"];
NSData *data = [dateNowString dataUsingEncoding:NSUTF8StringEncoding];
[fileHandle writeData:data];

if (i == 10) {
[timer invalidate];
[fileHandle closeFile];
}
i++;
}

@end

main.m

#import <Foundation/Foundation.h>
#import "Log.h"

int main(int argc, const char * argv[]) {
@autoreleasepool {
// insert code here...

Log *write = [[Log alloc] init];
[write log];

}
[[NSRunLoop currentRunLoop] run];//NSTImer 和 NSRunLoop 配合使用
return 0;
}