Objective-C基础知识总结

NSRange

NSRange range = [self.displayLabel.text rangeOfString:@"."];

typedef struct _NSRange {
    NSUInteger location;
    NSUInteger length;
} NSRange;

如果字符串中未包含字符，那么range.location=NSNotFound

CGFloat

Just a floating point number, but we always use it for graphics.

CGPoint
C struct with two CGFloats in it: x and y. 

CGPoint p = CGPointMake(34.5, 22.0); p.x += 20; // move right by 20 points

CGSize
C struct with two CGFloats in it: width and height. 

CGSize s = CGSizeMake(100.0, 200.0);

s.height += 50; // make the size 50 points taller

CGRect
C struct with a CGPoint origin and a CGSize size.
CGRect aRect = CGRectMake(45.0, 75.5, 300, 500);
aRect.size.height += 45; // make the rectangle 45 points taller 

aRect.origin.x += 30; // move the rectangle to the right 30 points

Enumeration

 NSDictionary *myDictionary = ...;
   for (id key in myDictionary) {
// do something with key here
id value = [myDictionary objectForKey:key];
// do something with value here }

Think of @“string” as autoreleased