iOS內存優化之NSTimer存在的內存泄漏

  最近開始進行內存優化了，先從NSTimer的內存泄漏做起，NSTimer的造成內存泄漏的主要原因就是循環引用，NSTimer如果只響應一次的話是不存在循環引用的。主要是repeat爲YES時才存在循環引用。其中timer需要執行必須要加到runloop中才可以，schedule開頭的方法默認加入了NSdefaultModel了，但是加入runloop會對timer進行一個強持有。timer的target也會被timer強持有，造成target的dealloc不會被觸發
循環主要有兩種方式

1，定時器響應爲block時，需要配合@weakify(),@strongify()來消除循環引用
2, 定時器響應爲selector時。需要中介者來作爲timer的target，timer觸發的方法被轉發給真正的target這樣就OK了。

參考博客地址：NSTimer避坑指南
非常感謝作者詳細的分析，大家可以多多的關注作者，多多支持。
根據作者的文章，我這邊對通過中介者對NSTimer進行了優化，主要是優化有兩點就是NSTimer的響應爲selector時，不存在循環引用了，並且NSTimer會自動釋放，不需要開發者手動釋放，NSTimer響應爲block時，仍然用@weakify(),@strongify()來避免循環引用，但是NSTimer可以自動釋放，不用開發者自己手動去釋放了。
具體代碼如下：

import <Foundation/Foundation.h>

NS_ASSUME_NONNULL_BEGIN

@interface NSTimer (JKBasicProvider)
/**
 普通定時器，自動加入Default類型的runloop中
 */
+ (NSTimer *)jk_scheduledTimerWithTimeInterval:(NSTimeInterval)interval
                                        target:(id)target
                                        repeat:(BOOL)repeat
                                         block:(void(^)(NSTimer *timer))block;

/**
 普通定時器，需要手動添加至runloop中
 */
+ (NSTimer *)jk_timerWithTimeInterval:(NSTimeInterval)interval
                               target:(id)target
                               repeat:(BOOL)repeat
                                block:(void(^)(NSTimer *timer))block;

/**
普通定時器，自動加入Default類型的runloop中
*/
+ (NSTimer *)jk_scheduledTimerWithTimeInterval:(NSTimeInterval)interval
                                        target:(id)target
                                      selector:(SEL)selector
                                      userInfo:(nullable id)userInfo
                                       repeats:(BOOL)repeat;

/**
 普通定時器，需要手動添加至runloop中，可以進行暫停，重啓操作
 */
+ (NSTimer *)jk_timerWithTimeInterval:(NSTimeInterval)interval
                               target:(id)target
                             selector:(SEL)selector
                             userInfo:(nullable id)userInfo
                              repeats:(BOOL)repeat;
@end

#import "NSTimer+JKBasicProvider.h"

@interface JKTimerTarget : NSObject

@property (nonatomic,weak) id actionTarget;
@property (nonatomic,copy) void(^actionBlock)(NSTimer *timer);
@property (nonatomic, assign) SEL actionSelector;

@end

@implementation JKTimerTarget

- (instancetype)initWithSelector:(SEL)aSelector
                    actionTarget:(id)actionTarget
{
    self = [super init];
    if (self) {
        self.actionBlock = nil;
        self.actionTarget = actionTarget;
        self.actionSelector = aSelector;
    }
    return self;
}

- (instancetype)initWithBlock:(void(^)(NSTimer *timer))block
                 actionTarget:(id)actionTarget{
    self = [super init];
    if (self) {
        self.actionBlock = block;
        self.actionTarget = actionTarget;
    }
    return self;
}

- (void)timerAction:(NSTimer *)timer{
    if (self.actionTarget == nil) {
        [timer invalidate];
        timer = nil;
    }else{
        if (self.actionBlock) {
            self.actionBlock(timer);
        }else{
            IMP imp = [self.actionTarget methodForSelector:self.actionSelector];
            void (*func)(id, SEL,NSTimer *) = (void *)imp;
            func(self.actionTarget, self.actionSelector,timer);
        }
    }
}

@end


@implementation NSTimer (JKBasicProvider)

+ (NSTimer *)jk_scheduledTimerWithTimeInterval:(NSTimeInterval)interval
                                        target:(id)target
                                        repeat:(BOOL)repeat
                                         block:(void(^)(NSTimer *timer))block
{
    JKTimerTarget *timerTarget = [[JKTimerTarget alloc] initWithBlock:block actionTarget:target];
    NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:interval target:timerTarget selector:@selector(timerAction:) userInfo:nil repeats:repeat];
    return timer;
}


+ (NSTimer *)jk_timerWithTimeInterval:(NSTimeInterval)interval
                               target:(id)target
                               repeat:(BOOL)repeat
                                block:(void(^)(NSTimer *timer))block
{
    JKTimerTarget *timerTarget = [[JKTimerTarget alloc] initWithBlock:block actionTarget:target];
    NSTimer *timer = [NSTimer timerWithTimeInterval:interval target:timerTarget selector:@selector(timerAction:) userInfo:nil repeats:repeat];
    return timer;
}

+ (NSTimer *)jk_scheduledTimerWithTimeInterval:(NSTimeInterval)interval
                                        target:(id)target
                                      selector:(SEL)selector
                                      userInfo:(nullable id)userInfo
                                       repeats:(BOOL)repeat
{
  JKTimerTarget *timerTarget = [[JKTimerTarget alloc] initWithSelector:selector actionTarget:target];
    NSTimer *timer = [NSTimer timerWithTimeInterval:interval target:timerTarget selector:@selector(timerAction:) userInfo:userInfo repeats:repeat];
    return timer;
}


+ (NSTimer *)jk_timerWithTimeInterval:(NSTimeInterval)interval
                               target:(id)target
                             selector:(SEL)selector
                             userInfo:(nullable id)userInfo
                              repeats:(BOOL)repeat
{
    JKTimerTarget *timerTarget = [[JKTimerTarget alloc] initWithSelector:selector actionTarget:target];
    NSTimer *timer = [NSTimer timerWithTimeInterval:interval target:timerTarget selector:@selector(timerAction:) userInfo:userInfo repeats:repeat];
    return timer;
}

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