NSTimer作为一个经常使用的类，却有一个最大的弊病，就是会强引用target。造成调用timer很麻烦。稍有不慎就造成内存泄漏。

下面就是为解决问题做的封装。

直接上代码：

#import <Foundation/Foundation.h>

@interface LZLTimer : NSObject

-(void)startTimerInterval:(NSTimeInterval)ti target:aTarget selector:(SEL)selector userInfo:(id)userInfo repeats:(BOOL)yesOrNo;

@end

#import "LZLTimer.h"

@interface LZLWeakTimerTarget : NSObject

@property (nonatomic,weak) id target;

@property (nonatomic,assign) SEL selector;

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

@end

@implementation LZLWeakTimerTarget

- (void)timerDidFire:(NSTimer *)timer {

    if(_target) {

        //消除arc警告

        IMP imp = [_target methodForSelector:_selector];

        if ([NSStringFromSelector(_selector) hasSuffix:@":"]) {

            void (*func)(id, SEL, id) = (void *)imp;

            func(_target, _selector, timer);

        }else {

            void (*func)(id, SEL) = (void *)imp;

            func(_target, _selector);

        }

    } else {

        [timer invalidate];

    }

}

@end

@interface LZLTimer () {

    NSTimer *_timer;

}

@end

@implementation LZLTimer

-(void)dealloc {

    if (_timer!=nil) {

        [_timer invalidate];

        _timer = nil;

    }

}

-(void)startTimerInterval:(NSTimeInterval)ti target:aTarget selector:(SEL)selector userInfo:(id)userInfo repeats:(BOOL)yesOrNo {

    if (nil == _timer) {

        WMWeakTimerTarget *weakTarget = [[WMWeakTimerTarget alloc] init];

        weakTarget.target = aTarget;

        weakTarget.selector = selector;

        _timer = [NSTimer scheduledTimerWithTimeInterval:ti target:weakTarget selector:@selector(timerDidFire:) userInfo:userInfo repeats:yesOrNo];

    }

}

@end