Programming-Idioms.org

NSLog(@"Hello world\n");

for (NSInteger i=0;i<10;i++){
NSLog(@"Hello world");
}

void foo(void) {
	NSLog(@"My job here is done. Goodbye\n");
}

int square(int x) {
  return x*x;
}

typedef struct {
  double x,y;
} NSPoint;

for (id x in items) _doSomething(x);

[items enumerateObjectsUsingBlock:^(id x, NSUInteger i, BOOL *stop) {
  NSLog(@"Item %lu = %@",(u_long)i,x);
}];

NSDictionary *x=@{@"one":@1, @"two":@2};

@interface Node:NSObject
@property id value; // id means any object value
@property Node *left,*right;
@end

// usage like
Node *n=[Node new];
n.value=@1;
n.left=otherNode;
n.right=anotherNode;

// somewhere needed also
@implementation Node @end

x.shuffledArray

x[arc4random_uniform(x.count)]

[list containsObject:x];

for (NSString *k in mymap)
  NSLog(@"Key %@, value %@",k,mymap[k]);

float pick(float a,float b) {
  id<GKRandom>  rnd=GKMersenneTwisterRandomSource.sharedRandom;
  float ru;
  while ((ru=rnd.nextUniform)==1);
  return a+ru*(b-a);
}

a+arc4random_uniform(b+1)

@interface Node:NSObject
@property id value; // id means any object value
@property NSMutableArray *children;
@end

// usage like
Node *n=[Node new];
n.value=@1;
[n.children addObject:otherNode];
[n.children removeLastObject];

// somewhere needed also
@implementation Node
-(instancetype)init {
  if (!(self=[super init])) return nil;
  _children=[NSMutableArray array];
  return self;
}
@end

x.reverseObjectEnumerator.allObjects

NSIndexPath *search(NSArray *m,id x) {
  NSUInteger j,i;
  for (i=0;i<m.count;i++) {
    if ((j=[m[i] indexOfObject:x])!=NSNotFound)
      return [NSIndexPath indexPathWithIndexes:&i length:2];
  }
  return nil;
}

__typeof(a) _temp=a; a=b; b=_temp;

int i=s.intValue

NSString *s=@"ネコ";

NSArray *x=@[
  @[@0.1, @0.2, ... ], // n column values
  ... // m rows
];

NSArray *x=@[
  @[
    @[@0.1, @0.2, ... ], // p column values
    ... // n sub-rows
  ],
  ... // m rows
];

[items sortedArrayUsingDescriptors:@[[NSSortDescriptor sortDescriptorWithKey:@"p" ascending:YES]]]

[items removeObjectAtIndex:i];

unsigned f(unsigned i) {
  return i?i*f(i-1):1;
}

unsigned exp(unsigned x,unsigned n) {
  switch (n) {
    case 0: return 1;
    case 1: return x;
  }
  if (n&1) return x*exp(x*x,(n-1)/2);
  return exp(x*x,n/2);
}

t=[s substringWithRange:NSMakeRange(i,j-i)]

BOOL ok=[s containsString:word];

NSMutableString *t=[NSMutableString string];
[s enumerateSubstringsInRange:NSMakeRange(0,s.length)
  options:NSStringEnumerationReverse|NSStringEnumerationByComposedCharacterSequences
  usingBlock:^(NSString *part, NSRange r1, NSRange r2, BOOL *stop) {
    [t appendString:part];
}];

[m enumerateObjectsUsingBlock:^(NSArray *row, NSUInteger rn, BOOL *stopr) {
  [row enumerateObjectsUsingBlock:^(NSNumber *v, NSUInteger cn, BOOL *stopc) {
    if (v.intValue<0) {
      NSLog(@"found %@ at row:%lu col:%lu",v,rn,cn);
      *stopr=*stopc=YES;
      return; // to quit the current block immediately
    }
  }];
}];

[NSThread sleepForTimeInterval:5.0];

NSString *t=[s substringToIndex:5];

NSString *t=[s substringFromIndex:s.length-5];

NSString *s=@"Huey\n"
            @"Dewey\n"
            @"Louie";

NSArray *chunks=[s componentsSeparatedByString:@" "];

for (;;);

if (m[k]) ...

NSString y=[x componentsJoinedByString:@", "];

id s=[x valueForKeyPath:@"@sum.self"];

NSString *s=@(i).description;

NSArray *y=[x filteredArrayUsingPredicate:p];

NSString *lines=[NSString stringWithContentsOfFile:f encoding:e error:NULL];

NSLog(@"%d is negative",x)

NSDate *d=NSDate.date;

int main(int argc, char *argv[])
{
    while (*++argv) {
        printf("%s", *argv);
        if (argv[1]) printf(" ");
    }
    printf("\n");
    return EXIT_SUCCESS;
}

int main() {
  NSArray *all=NSProcessInfo.processInfo.arguments;
  NSArray *args=[all subarrayWithRange:NSMakeRange(1,all.count-1)];
  puts([args componentsJoinedByString:@" "].UTF8String);
  return 0;
}

do ... while(c);

BOOL b=[s hasPrefix:prefix];

// once
static NSDateFormatter *df; 
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
  df=[[NSDateFormatter alloc] init];
  df.locale=[[NSLocale alloc] initWithLocaleIdentifier:@"en_US_POSIX"];
  df.timeZone=[NSTimeZone timeZoneForSecondsFromGMT:0];
  df.dateFormat=@"yyyy-MM-dd";
});
// then, wherever needed
NSString *x=[df stringFromDate:d];

[items sortUsingComparator:c];

BOOL blank=![s stringByTrimmingCharactersInSet:NSCharacterSet.whitespaceCharacterSet].length;

NSUInteger n=x.count;

NSSet *y=[NSSet setWithArray:x];

[NSSet setWithArray:x].allObjects

scanf("%d",&n);

typedef NS_ENUM(int, Suit) {
  SPADES, HEARTS, DIAMONDS, CLUBS
};

if (c1) f1();
else if (c2) f2();
else if (c3) f3();

NSArray *items=@[a,b,c];

id nodigit=[[NSCharacterSet characterSetWithRange:NSMakeRange('0',10)].invertedSet copy];
BOOL b=![s rangeOfCharacterFromSet:nodigit].length;

NSString * const Planet=@"Earth";

x=items.lastObject;

NSArray *ab=[a arrayByAddingObjectsFromArray:b];

NSUInteger n=s.length;