int test(int x, int y)
{x = x + y;return x * y;
}int main(int argc, const char * argv[])
{@autoreleasepool {int x = 3, y = 10, z = test(x, y);NSLog(@"%d%d", x++, ++z);}return 0;
}

int func(int x)
{int countx = 0;while (x) {countx++;x = x&(x-1);}return countx;
}int main(int argc, const char * argv[])
{@autoreleasepool {NSLog(@"%d", func(2013));}return 0;
}

for (i = 0; i < N; i++) {if (condition) {doSomeThing();} else {doOtherThing();}
}if (condition) {for (i = 0; i < N; i++) {doSomeThing();}
} else {for (i = 0; i < N; i++) {doOtherThing();}
}

UIView *tmpView = [[UIView alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
[self.view addSubview:tmpView];

@interface Manager : NSObject
+ (id)sharedManager;
@end

static Manager *instance = nil;@implementation Manager+ (id)sharedManager
{if (!instance) {instance = [[super allocWithZone:NULL] init];}return instance;
}// 复写allocWithZone和copyWithZone的目的是在外部多次调用alloc的时候，内部能够确保对象只创建了一次+ (id)allocWithZone:(NSZone *)zone
{return [[self sharedManager] retain];
}- (id)copyWithZone:(NSZone *)zone
{return self;
}// 复写retain、retainCount、release、autorelease避免单件对象被外部释放
- (id)retain
{return self;
}- (NSUInteger)retainCount
{return NSUIntegerMax;
}- (void)release
{}- (id)autorelease
{return self;
}

@protocol ADelegate;
@interface A : NSObject@property (nonatomic, assign) id<ADelegate> delegate;- (void)go;@end@protocol ADelegate <NSObject>- (void)doSomeThing;@end

@implementation A- (void)go
{if ([_delegate respondsToSelector:@selector(doSomeThing)]) {[_delegate doSomeThing];}
}@end

#import "A.h"@interface B : NSObject<ADelegate>@end

@implementation B- (void)doSomeThing
{NSLog(@"do something...");
}@end

#import "A.h"
#import "B.h"int main(int argc, const char * argv[])
{@autoreleasepool {A *a = [[A alloc] init];B *b = [[B alloc] init];a.delegate = b;[a go];[a release];[b release];return 0;}
}

char a[] = "hello world";
char *p = a;NSLog(@"%ld", sizeof(a));
NSLog(@"%ld", sizeof(p));

@interface NSCustomArray : NSArray
@property (nonatomic, retain) NSArray *targets;
- (void)updateTargetsByArray:(NSArray *)newArray; // 将newArray赋值给targets
@end

@implementation NSCustomArray- (void)updateTargetsByArray:(NSArray *)newArray
{NSArray *tmpArray = [[NSArray alloc] initWithArray:newArray];// 将tmpArray赋值给targets
}
@end

- (void)setTarget:(NSObject *)target
{self.target = target;
}

- (void)willEndStepOne:(NSObject *)userInfo
{[NSThread detachNewThreadSelector:@selector(doSomeThing:) toTarget:self withObject:userInfo];
}- (void)doSomeThing:(NSObject *)userInfo
{int max_loop_times = 999999;for (int i=0; i<max_loop_times; i++) {int randNum = rand();NSString *tmpString = [NSString stringWithFormat:@"%d", randNum];NSLog(@"%@", tmpString);}
}